question

Dear Amazon, We have read the documentations, and numerous customer questions regarding how to determine the expiration date of a subscription. The Amazon Receipt Validation Server returns null if the subscription is active. However, for a subscription that can be utilized cross-platform (Website, TV Apps, Android Apps, etc.) and beyond the Amazon App, it is necessary and efficient to know and record the actual subscription expiration date. Below are my questions: 1) If the user logs into our website or one of our TV App to utilize their subscription, should our website or TV app immediately communicate back to our Server to query the Amazon Receipt Validation Server in other to determine if the user's subscription was still active each, and every time the user logs into our website or our one of our TV Apps? 2) Is there a more efficient way to determine an expiration date of a subscription without having our server query the Amazon Receipt Validation Server for each outlet (Website, TV Apps, Android Apps, various smartphones, various tablets) from which our subscription can be utilized? 3) Our centralized platform already has a database field for a subscription "expiration_date" that is populated regardless of the subscription payment provider. What do we store in the "expiration_date" field for subscriptions that were purchased via Amazon In-App Payment without writing specialized code that will affect all our outlets, and query the Amazon Receipt Validation Server each and every time a person logs in? We will greatly appreciate answers that will help us simplify the integration of Amazon In-App Payment subscription. Thank you.