So, if your friend brings a game over, he signs into his profile and it allows you to play the game on your system; when he signs out of his profile and leaves, the game is still installed on your system, but if you want to continue playing the game, you will have to pay to do so.
When you are finished with a game and you want to trade it in or sell it in another way, they will offer a mechanism that will allow you to take digital content and trade in a previously played game at a retail store; but Microsoft isn’t ready to announce how this will work. The good news is that they are going to have a way to do it.
The bottom line is that the digital rights management is going to be much tighter on the Xbox One and that is something that we are just going to have to get used to dealing with. More information is coming surrounding this and we can expect Microsoft to clarify things as we get closer to launch.