On Google and Apple we have launched a subscription model for our apps, and a subscription through one gives access to all of our apps. This is possible because Google and Apple will both send our server notifications about subscription renewals/cancellations/etc
Amazon on the other hand seems to rely on the original app to handle all receipts, and then send those to our server. The issue is this:
Image a user downloads and subscribes through App A
They then also download App B, C, and D and login to our server and we give them full access
At some point they cancel their subscription, but NEVER open up App A again. Well they still have access to Apps B, C, and D and will forever.
Am I missing something? Is there a way to handle this? Apple uses Server Notifications and Google uses Pub/Sub. Amazon needs something similar.