In the web funnel:
1. Implement an account creation flow in the web funnel (the purchase should be linked to a user ID so users can restore it via email, phone number, etc. There's an example available in our catalog.
2. Optionally implement deeplinks (nice to have – but you can postpone this until you're sure this channel works well for you).
Inside the app:
3. Implement the ability to log in during the early stages of the interface (a separate entry point if you plan to use deeplinks).
4. Implement subscription verification, taking into account that subscriptions may now come from two sources: iOS/Android and web.
5. Implement the ability for users to cancel their subscriptions.