How Do I Let Some Users To Install For Free A Paid Android App?

I am developing an Android application, and common users have to pay for it. But, I want to offer that application for free to my webpage users. I have a login in that webpage, so

Solution 1:

I fear installing without downloading is not possible, maybe you shoud think about a second version which needs a key (e.g. created by the device ID and a secret Prefix.

• User is downloading your apk
• User get the message he needs to register
• User send his Device ID to yor Webpage (and have to login before)
• Your Website create a hashkey with the device ID and a secret password
• The Application stored the key in the Preferences and will check at startup, if the stored key fit to the Device ID/password Hash.

Solution 2:

If you let some download your apk, then it just get downloaded. Users will have to install it manually and what is worse, they won't get updates through the common android market mechanism.

Solution 3:

if they have rooted phone then they can do anything with your apk. there is no security in android even you can get the source code of an app. in your case the only way is to implement certificates.