Best flow for subscription service app?


I am creating an app that follows a subscription model. Quite simple really, a user signs up inside the app and receives some free content. If they want access to all of the content they need to subscribe.

I have built the API for this content, as well as auth (I have my own oauth implementation with access tokens working). Previously the model was to have the user sign up for the premium content on the website. The access token would then let us/the app know whether the user had access to premium content or not (premium content is fed via the API, so this is a secure method).

We’re now looking to move the purchases to an in-app subscription model using in-app purchases instead. The user won’t be able to purchase away from the app at all.

I’m a little unsure how to manage this and I’m unable to find any clear resources online around it. I know I can use Ionic’s native APIs to create a subscription within Google Play and iOS App Store, but what is the standard way of handling that in conjunction with an API? I’ll need to store the subscription status in our backend in some capacity surely? And in order to do that we’ll need updates when the subscription lapses.

So I guess my questions are:

  1. How do we keep up-to-date with subscription statuses on our backend?
  2. Do we even need to? Is this logic kept within the app? (Seems insecure)
  3. Are there any resources out there around this?