In-app purchasing means buying digital goods and services within the app. What does that mean for developers? It means another great way to make money.
Google Play Billing allows you to sell items and additional features, or to remove ads. Google Play handles the checkout details so your app never has to process financial transactions and user gets a familiar, reliable, and secure experience.
This demo Android app demonstrates implementation of in-app purchasing with google library for one-time products (no subs).
You can read more about it here : https://medium.com/@surabhichoudhary/in-app-purchasing-with-google-play-billing-library-6a72e289a78e