Thus if for example, you purchase DA:O from the US then move to Japan, you will no longer be able to play your purchased game. If you ask someone to gift the game to you from the US, you will not be able to play your gift. Details can be found here:
So be aware, Valve now enforce access to your games based on your current IP and no longer apply restrictions for Steam store bought games at the point of purchase only. Expect this feature to be expanded upon in the near future to affect more regions and more games.
News thanks to DAO_Japan. You can discuss this issue here.