The CD Key you used to activate the game was revoked by the publisher of the game. This can happen, for example, when the CD Key is intended for a limited time activation, like a Beta, or if the publisher determines that the CD Key itself had been obtained by fraudulent means.
Your account will not be restricted; however, the CD Key you received will be removed. If you would like to play the game again in the future, you will need to purchase it from the Steam Store, activate another CD Key, or redeem a gift copy of the title.
If you or someone you know purchased this CD Key through a third party website, we suggest contacting the seller to request a refund. We have no way to issue refunds for purchases made outside of Steam.