I was watching Superleague this morning, Dreamhack was starting up. So I used the ticket while I was spectating the game. I got a message in-game saying "You have no more charges on your Asus Dreamhack blahblah ticket". However, I noticed later on I still had a ticket in my inventory, and I had the ticket icon on my profile and I can spectate games just fine.

I even noticed that I could put up the ticket on the Steam Community Market, but my conscious got the best of me.

Am I allowed to sell it without fear of Valve banning/taking away my items or do I wait until a mod or something takes it from me?