Hello i’ve got the same problem, i’ve bought two cd key from steam one for a friend and the other one for me so i paid 14.99 for me and 14.99 for my friend.
Last week i can’t play, the game has gone of my steam account but my friend still have the game i don’t understand.
The steam support said that my cd key has revoked by the editor, what can i do? i still have the paypal payement information that proof i have buy the game.
sorry for my english i’m french

by Tibberius » Wed Mar 06, 2013 5:22 pm

This was actually done at the request of the Humblebundle.com guys who run our widget on our site. It seems that some companies or persons were cheating the system with fraudulent purchases and defaulting on them only to later resell them from other outlets. We have agreed with Humble Bundle’s request to shut the keys off in order to curb efforts by these companies to continue this practice of stealing keys along with increased security measures on the widgets.

This is also why the buy from us page was down for so long. You will need to take up issues with the site you purchased from, which sold you stolen keys.