When a user first purchases a subscription from the Google Play Store, my app sends my server a receipt which contains the package name, the subscription/product ID, and the purchase token. I can then call the Purchases.subscriptions.get API to verify the subscription.
What I am unclear about is whether I can verify the subscription entirely server side once a renewal happens? The docs are pretty unclear about this.
As I understand it, with the V3 purchases API the app needs to poll to see if a subscription has been renewed and then forward the new receipt onto the server. I assume the purchase token would be different across renewals, which would suggest that it's not possible to implement renewal checks entirely server-side.
Am I missing anything?