Before providing the end user with free access, ensure that they have
unscubscribed from the paid subscription. Otherwise, they will continue to
be charged for the subscription by the App store and the Play store.
Check this link:
https://audiorista.zendesk.com/hc/en-us/articles/4403056712081-Refunding-a-Subscription
on how to refund a subscription.
Firebase
1. Go to Firebase.
2. In the Authentification section, click on Add User. If the user already exists, find the user by using the search bar, and proceed to step 3.
3. Add the email address and password for the user.
4. Copy the User UID on the right-hand side by clicking on the copy-symbol.
RevenueCat
5. Go to RevenueCat.
6. In the search bar under Find Customers to the left-hand side, enter the copied UID.
7. You will end up on the Customer profile. On the right side, in Grant Entitlement, you can change the type of entitlement and the duration. Once you have chosen, click on Grant.