CD Key

Hi i got a problem -... i buyed Need For Speed Hot Pursuit on steam .. i instal it,register,Put the cd key  and with no problems i played with my freinds the game on autolog .... after reinstaling the windows i again instal it and when i log in and want to play online it ask me for Cd key so i put the cd key which steams show me and it says This cd key was used multipal times and if i want to enter another key ...now the problem is i cant play it becuase i dont have another cd key to the game... then i tried to copy the cd key put it on origin the game succesfully instaled but the same problem with the cd key when i log in and want to play with my freinds ... pls help me with this 

Thank you