Refund & Cancellation Policy

Last updated: September 8, 2026

This policy explains how billing, cancellation, and refunds work for EulerVertex, operated by Mathhead, Inc. ("we", "us", "our"). It forms part of our Terms of Service and should be read together with our Privacy Policy.

Summary. You can cancel a subscription at any time and keep access until the end of the period you have already paid for. If you are a first-time subscriber, you can request a full refund within 14 days of your first payment. Renewal payments are not refundable. Unused credits can be refunded within 14 days; credits you have already spent cannot. A paid weekly-allowance refresh, once applied, is not refundable.

Questions or requests: service@eulervertex.com.

1. Scope

This policy covers purchases you make directly from us through our online checkout, processed by Stripe, Inc. It applies to:

  • Subscriptions — recurring monthly or annual plans giving access to paid content and features.
  • Credit packs — where offered, prepaid credits consumed by certain features.
  • Weekly allowance refresh — where offered, a one-time payment by a Pro subscriber that resets the current week's usage to zero.

It does not cover purchases made through a third party such as an app store or reseller (their refund rules apply instead), or any agreement covered by a separate signed contract with an institution, which governs on its own terms.

Free accounts and free content involve no payment and nothing to refund.

2. Subscriptions: Billing and Automatic Renewal

Billing cycle. Subscriptions are billed in advance for the period you select — monthly or annual. Your first charge is taken when you subscribe.

Automatic renewal. Your subscription renews automatically at the end of each billing period, and your payment method is charged the then-current price for a further period, until you cancel. The renewal date and price are shown before you buy and in your account.

Price changes. If we change the recurring price of your plan, we will email you at least 30 days before the change applies, and it will only take effect from your next billing period — so you can always cancel first. See Section 5 of the Terms of Service.

Taxes. Prices exclude applicable taxes unless stated otherwise. Refunds include any tax we collected on the refunded amount.

3. How to Cancel

You can cancel at any time, and cancelling is straightforward:

  • In your account — open your subscription settings and choose to cancel; or
  • By email — write to service@eulervertex.com from the address on your account, and we will cancel it for you.

What happens when you cancel. Cancelling stops all future renewal charges. It does not end your current period — you keep full access to paid features until the end of the period you have already paid for, and your subscription then lapses to a free account.

Cancelling on its own does not produce a refund. If you want money back as well, see Section 4.

Timing. Cancel before your renewal date to avoid the next charge. If you cancel shortly after a renewal has been taken, contact us — see Section 5.

Your content stays. Cancelling does not delete your account, your work, or your content. You lose access to paid-tier material only. Account deletion is a separate request, described in our Privacy Policy.

4. 14-Day Money-Back Guarantee (First-Time Subscribers)

If you are subscribing for the first time and the Service is not right for you, we will refund your first payment in full — no explanation needed — provided you ask within 14 days of that payment.

How to claim. Email service@eulervertex.com from the address on your account, within 14 days of your first subscription charge, and say you would like a refund under the 14-day guarantee.

What happens. We cancel your subscription, refund the full amount of that first payment to your original payment method, and your paid access ends at that point.

Conditions. The guarantee applies once per customer, to your first paid subscription only. It does not apply to renewals (Section 5), to a subsequent subscription after you have previously subscribed and been refunded, or where we have terminated your account for breach of the Terms.

5. Renewal Payments

Renewal charges are not refundable, because you were told the renewal date and price in advance and could cancel beforehand.

That said, we are reasonable about honest mistakes. If you were charged for a renewal you did not intend — you meant to cancel, or did not realize the plan renewed — contact us within 14 days of the charge and we will normally refund it in full, provided you have made little or no use of the Service in that new period. This is offered in good faith and at our discretion, not as a right, and we may decline it if it is being used repeatedly.

6. Credits

Where we offer prepaid credits:

  • Unused credits may be refunded pro rata if you request it within 14 days of the purchase of that credit pack.
  • Credits you have already spent are not refundable. Once a credit has been consumed, the service it paid for has been delivered.
  • Credits have no cash value, are not legal tender or a stored-value instrument, cannot be transferred or exchanged between accounts, and cannot be redeemed for cash except where required by law.
  • No expiry. Purchased credits do not expire.
  • Consumption rates for a given feature may change on reasonable notice, as described in the Terms of Service.

If you cancel a subscription, any separately purchased credits remain on your account until used.

Weekly allowance refresh. A refresh resets your usage for the current week to zero straight away and does not change your regular weekly reset date. Because it takes effect immediately, it is not refundable once applied, except where it did not work as described. If your subscription had ended by the time your payment completed, the refresh could not be applied and we will refund it in full.

7. Your Right of Withdrawal (EEA and UK Consumers)

If you are a consumer resident in the European Economic Area or the United Kingdom, you normally have a statutory right to withdraw from a distance contract within 14 days without giving a reason.

Important — immediate access. EulerVertex is digital content supplied immediately. When you purchase, you expressly request that we begin supplying it at once, and you acknowledge that you therefore lose your statutory right of withdrawal once supply has begun. We present this to you at checkout.

This does not disadvantage you in practice, because our 14-day money-back guarantee in Section 4 gives first-time subscribers the same 14-day window voluntarily. Nothing in this policy limits any mandatory right you have under the consumer protection law of your country of residence, including your rights where the Service is faulty or not as described.

8. Faulty or Misdescribed Service

If the Service does not work as described, is unavailable for a prolonged period, or you were charged incorrectly, you are entitled to a remedy regardless of any time limit in this policy. Contact service@eulervertex.com and describe the problem. Depending on the circumstances we will fix the issue, extend your subscription, or refund you in full or in part.

If we discontinue a paid feature during a period you have paid for, we will refund the unused portion pro rata, as stated in Section 14 of the Terms of Service.

Note on AI accuracy. As explained in Section 12 of the Terms of Service, AI-generated explanations, generated problems, and automated grading can and do produce incorrect results. This is a known and disclosed characteristic of the Service rather than a fault, and individual incorrect AI output is not by itself a basis for a refund. If AI features are broadly unusable or unavailable, the rest of this section applies normally.

9. Exceptions

We may decline a refund where:

  • the request falls outside the applicable window and no statutory right or Section 8 remedy applies;
  • your account was terminated for breach of the Terms of Service;
  • we reasonably believe the request is fraudulent, abusive, or part of a pattern of repeatedly subscribing and refunding;
  • the purchase was made through a third-party store or reseller (ask them instead); or
  • credits have already been consumed, or have expired.

Where we decline, we will explain why.

10. How Refunds Are Issued

  • Refunds go back to your original payment method through Stripe. We cannot send a refund to a different card, account, or person.
  • We normally process approved refunds within 5 business days, and your bank or card issuer typically takes a further 5 to 10 business days to post it. The total time is outside our control.
  • Refunds are issued in the original currency of the purchase. If your bank applies currency conversion or fees, the amount you receive may differ slightly from the amount charged. We cannot compensate for exchange-rate movements or third-party bank fees.
  • We will email you when a refund has been issued.

11. Failed Payments

If a renewal payment fails, we may retry it over a short period and will email you. If it remains unpaid, we may suspend or downgrade your access to paid features until it is resolved. Your account and your content remain intact, and free features stay available.

12. Chargebacks and Disputes

Please contact us before disputing a charge with your bank. Almost every billing problem is quicker to resolve directly, and we would rather fix it than argue about it.

Filing a chargeback without contacting us first may result in your account being suspended while the dispute is investigated, and we may decline to serve accounts with a history of unwarranted chargebacks. If a chargeback is resolved in our favour, any suspension may remain until the balance is settled. This does not affect your right to dispute a charge you genuinely did not authorize.

13. Changes to This Policy

We may update this policy. When we do, we will revise the "Last updated" date above. The version in effect at the time of your purchase governs that purchase — changes do not apply retroactively. For subscriptions, a change applies from your next renewal, and we will give reasonable notice of any material change.

14. Contact Us

For cancellations, refund requests, or billing questions:

Please write from the email address on your account, and include the approximate date and amount of the charge so we can find it quickly. We aim to respond within 3 business days.