I want to make a subscription similar to this example:
I want a person to subscribe to a purchase of 10 monthly apples, but if he eats all 10, the first day the user can pay for a subscription of 20 monthly apples.
Do I have to cancel the old subscription and create a new one?
In the example above, as I tell the stores and RevenueCat, that the 30-day subscription is no longer valid because its apples have already been consumed and that a new subscription of 20 additional monthly apples will have to be created.
Sounds like you probably want to use non-subscription purchases instead. We have a doc on that here:
Things get tricky with cancelling subscriptions (e.g., iOS won’t let you manage a user’s subscription on their behalf).
If that doesn’t cover your use case, let me know and I’m happy to help troubleshoot!