app with server synchronization feature and recurring payment

Question

I made an Android app which synchronizes its data with an online server hosted by me. Users will be able to synchronize their data and also access a web interface (hosted on the same server) to manage their data (the web interface looks very similar to the app itself but it's more convenient for accessing the data while in front of a desktop PC). My question is: how can I let the user make a recurring payment to enable such feature? More specifically:

• Is it allow by Google terms and conditions to allow users to buy a login account on a website which has nothing to do with Google itself but that shares data with the app hosted on Google Play?
• Do I need to implement the payment as a recurring payment inside the app or can it be an external payment page hosted on my web server?
• If the payment has to be done inside the app, how can I let the server know about this?

Answer 1

• Is it allow by Google terms and conditions to allow users to buy a login account on a website which has nothing to do with Google itself but that shares data with the app hosted on Google Play? ->

Apps published on Google Play that are selling subscriptions must use In-app Billing to handle the transaction and may not provide links to a purchase flow outside of the app and Google Play (such as to a web site). Source

Add subscriptions and Recurring payment policy

• Do I need to implement the payment as a recurring payment inside the app or can it be an external payment page hosted on my web server?

->Apps published on Google Play that are selling subscriptions must use In-app Billing to handle the transaction and may not provide links to a purchase flow outside of the app and Google Play (such as to a web site).

• If the payment has to be done inside the app, how can I let the server know about this?

-> GCP allows developer with real time notification. source

Also you can implement Server validation using Order_Id and ProductPurchase Resource Source