Thank you for your interest in Amazon Appstore SDK Appstore Billing Compatibility SDK.
 
We are continually improving our APIs and recently introduced Appstore Billing Compatibility 4.0.0.
See https://developer.amazon.com/docs/in-app-purchasing/appstore-billing-compatibility.html 

If you need DRM for your Java Android app, you need to take some extra steps 
to incorporate some license checking functions in your app through the DRM API 
(available through the Appstore SDK).

Thanks,
Amazon Appstore