What I have accomplished :
Google Play billing works and I am able to purchase a subscription successfully.
What I want :
Now I want to add a notification feature every time the state of the subscription changes (ie. Renewal, Cancellation, etc.) Since subscriptions auto renews, I would like to notify the user every time it happens.
My problem :
I know how to make a simple notification, but my problem is when. How do I retrieve when the subscription starts (or renewal date), when it ends (or next renewal date). And how do I send the notification? Do I start a background service? I do not have a back end to implement the Google Cloud Pub/Sub