Q. Apps backup and restore

No, you don't need to re register again.

Sent from my LG-E986 using xda app-developers app

You cant restore apps from a unrooted phone. You need root. You can it do with titanium backup.

Sent from my LG-E986 using xda app-developers app

For non-rooted apk backup.

"Appmonster" is the one i am using now. It only will backup your added stuff easily. Different programs have different mechanisms for licencing, so there are some that certannly will have to re-connect with the store or something before they will be the paid version. Others that it is a part added securely, and one (piece of crap) wanted to licence verify every day. Appmonster does not backup extra external data stuff, So i do that manually, and again it might still have to connect to finish. or check licence.
there are 2 others that do the simple backup installed apps to apk packages, both worked (unrooted) for what you can do unrooted, i just happen to be using appmonster because it was simple, and aimable to a folder. Some paid programs are not able to be backed up with it, some secured stuff .

Try Helium too. Need to hook up to a PC for it to work though. Works with uprooted.

Sent from my LG-E980 using XDA Premium 4 mobile app