android - InApp Subscriptions or Google Wallet -

I have gone through a lot of links on Stackshowourflow and I have an in-app approval and some doubts about Google Wallet.

What do I know:

1. Basically the app helps the user subscribe to the app, for example it would provide a one-year trial period Once again, Google automatically handles subscription after that.
2. Google Wallet, this is a method that can be used to make purchases. I can not understand why I can use this method so that users can use one-year app, and then pay them for next years?

Membership is essentially ongoing at the specified intervals and prices for membership. On each subscription renewal, Google Play automatically charges the user account, then notifies the user of the fee by email later, for monthly and annual subscription, depending on the purchase cycle, the billing cycle will always match the membership cycle . (Seasonal membership is charged annually on the first day of the season.)

This is in my app: 1. A user logs in, and I get that date Which probably holds track of the billing cycle 2. If the session has expired, then the user is asked to pay to use the Input Billing Services 3. Based on the TrivailDriveApp example, where we have a successful log on the subscription, we update the date of payment.

I have a few questions:

1. According to the quote from Android, if the user automatically subscribes to the service, and if the mail is sent to the user Does this mean that I will never be able to get a notification about the payment extension? How do I sync with that server?

2. Is my view wrong in dealing with this kind of scenario? Or do I have to choose a different method to handle app extensions?

PS: There is no way to test InPay subscriptions too. I wonder if I can do this without using actual credit / debit card credentials.

Edit:

Even when I was purchased or billing, if the subscription is auto-renewal, then instead of an inapp membership Should the purchase flow take as an InApp product?

Please help.