Subscriptions on Untapped.gg renew automatically, until you indicate that you would like to end your subscription. You can do this by the following steps:

First, please confirm you've actually canceled your subscription on the billing page:

Billing Settings

Your subscription is canceled if you are presented with a date on which the subscription ends or terminates.

If you've stopped using the product, forgot to cancel the subscription and an unexpected payment happened recently, please contact us as soon as possible. On a case-by-case basis you may be eligible for a refund.