STEAM AND VALVE SUPPORT
HOW TO INSTALL STEAM
1. Download and install STEAM from http://store.steampowered.com/about/
2. Login to your STEAM account and you are able to access your game in the library.
ACTIVATING A PRODUCT KEY
1. Click on “ADD A GAME” at lower left corner of STEAM platform and select “Activate a product on STEAM”.
2. Key in your CD-Key .
IS THERE A LIMIT TO THE NUMBER IF MACHINES THAT CAN BE AUTHORIZED AT ONCE?
No, there's no limit. Steam Guard is aimed to protect the value that is yours, not limit your access to your stuff.
As always, you can access your Steam account and library from as many machines as you'd like.
Learn more about STEAM GUARD here - http://steamcommunity.com/sharedfiles/filedetails/?id=153396149
RECLAIMING A HIJACKED STEAM ACCOUNT - HOME USER
How can I reclaim a lost or hijacked Steam account?
Submit a Ticket to Steam Support