The version without those 5 lines will now be forever out there though. Malicious peers can download the apk and get the premium version for free. This feels like a poorly thought out design on Google's part.
Obviously if you decompile the application and modify it you can get the premium features for free. What’s your point?
numerlo is saying that users don't even need to decompile the app - they can continue sharing the buggy APK with each other to get free stuff.