For a while this game was pay to play, you needed a cd-key to activate your account.
If you are too young to know this, back in the day to stop people from pirating games each game sold had a unique CD Key for example FDS13-D34AD-934AA-IOH55 that you need to enter when you install the game.
In Toribash you added the key to your account which you log in to the game with.
If I remember correct it was pay to play around 07 some time (definitely by mid 07) to early 08 (definitely gone by mid 0
, though I can't remember exactly when, maybe it was earlier than that... Price was something like $15
Well, all that said, it's not really a cd key since there is no cd, it's a registry key (called a reg key)