Developers have been asking us how to distribute free versions of their apps to users but with a path to monetization. We have introduced a way for developers to deliver a free trial version of their app, maybe with limits on the number of levels to play, or only a certain amount of time to play before ending, giving the user an incentive and path to upgrade to the full version of the app.
Just build two versions of your app — the full version and the limited “Trial” version. When you are ready to submit your app, upload both the full and the trial APKs.
When the customer is considering your application, they can choose to purchase or get the Free Trial version. See this example purchase dialog:
Customers can try your app and use it until they reach the limit you have set. You choose how to present the up-sell opportunity to buy the app. For example, see this splash screen with an “Upgrade Now!” button:
Pressing the button downloads the full version which replaces the trial version and is still able to access any user or game data that has already been created during the use of the trial version. The trial version uses the Shop Intent with the EAN (unique ID) of the for-pay version to present the offer to upgrade to the full version.
See the following article for more information: https://nookdeveloper.zendesk.com/entries/20126777-how-do-i-build-a-trial-version-of-my-app

