I believe it's against steams TOS to sell or even lend your account to a friend.


I remember a guy I used to play online a lot with & made 'internet friends' with lent his account to his friend who of course was on a different Ip and his account got suspended, because he didn't give steam notice.


However I know people who have changed ip and haven't had a problem so its all luck  I guess.


You might want to check out the TOS though, it is not allowed.