Cod 5: WaW serial key help!

hello.

I have an cod 5 serial key (legal) and im playing on official servers.
but is it possible that when i go to my friends house and type in my serial key and play on legal servers with him while im there.

will it be possible to play again when im back home?
after is deleted the game there.

So bassicly kinda share my serial while im there