Can I secure my APK files that I created with Adobe Air and Flash CC 2015 ?

Hi

Im devloping with Flash CC 2015 and I have 5  Apps on the Appstore.

On Android I have 2 and the are not selling. Reason is that everybody can just copy (crack) the APK file.

On Appstore I have a provisionfile which does the job.

Can anyone help me to secure my Android Apps, so nobody is able to just copy it ?.

regards

Michael