In-app billing is a big money maker for the top apps on Google Play. According to Google’s stats, the “vast majority of top-grossing apps” use in-app billing in a variety of ways including try-and-buy, virtual goods, and subscriptions. Now Google is further improving in-app billing for even more chances at striking it rich on Google Play.

Google announced that in-app billing version three is now available to developers. It includes a number of new features such as:

In-app billing is supported by all Android devices running Android 2.2 or higher. It also requires the latest version of the Google Play store. It only supports in-app item purchases for now, but Google is bringing subscriptions back shortly.

Developers will be pleased to know that the new version of the in-app billing API is no longer asynchronous. Previous incarnations of the API required developers to make use of four different application requests. Now all requests and responses are handled within a single activity and accomplished with just a few lines of code.

Aside from the new features and improvements, Google is also offering a sample application that will show developers how to implement in-app billing in their apps. Google also notes that In-app billing version three introduces app-specific keys. These will replace the developer-specific keys that were used before. Now developers will have to retrieve Licensing and in-app billing keys on a per app basis. With that being said, existing applications can still use their old keys.

Check out the Android developer blog post to see some specific examples of the new code in action. While you’re at it, you might want to check out the new documentation for in-app billing and selling in-app products. To start using the new in-app billing version three, just hit up the Google Play Developer Console preview.