Where to save player progress?

I am making a simple mobile game in Unity and it will include a in-app purchase for virtual coins. Now I wonder what if player change phone, buy new one,..., and install the game again on new phone, from where he could get back all purchases which he made during playing game on old phone? Is this solved inside each store with some kind of plugin or what? Has it Unity something for handle this issue? I made in Unity a procedure for saving coins, score, etc but it is local solution. What is the best practice for solving that problem? Any suggestions?

Denis