Hi, My friend recently bought used Macbook Air. He formated the system partition and now he can only boot into Lion Recovery partition. Now he wanted to install Mavericks but when I gave him the usb key it wouldt work on his mac, as I mentioned in other thread here. So now the only option is to reinstall Lion from recovery disk and than upgrade to Mavericks. But as he bought the mac used he doesn't have a licence for Lion and upon installation when he signs in mac app store it gives him an error that he cannot install lion because he hasn't purchased it. Now since Mavericks is free he is of-course not going to buy Lion, the question is: can I enter my account in there (I bought Lion when it came out) and install it like that, than upgrade and sign out and sign him in? Will that in any way effect my account on the app store?