In-App Billing Purchases
This method is only available for versions with an Extended License.
in order to use the Google in-app purchase payment system in your mobile application, you will need to follow a few steps in the google play console as there are a few rules you should know.
There should be a temporary APK file Uploaded to Google play in order to fetch the Product ID (In-app License code) so you can proceed with your Build and package prices.