Transfer paid apps from iPhone to Android Account
The Apple App Store and the Google Play Store are two different stores. 
It is in their best interest to make it impossible/not allow anyone to transfer an app from one store to another.

It's like how you can't buy a phone from Samsung and then claim on the warranty with Apple.
It's often possible to transfer progress in games across platforms but you have to buy the app a second time, sadly.

You can transfer almost anything from iOS to Android but not apps.