Get half-life CD key from Steam

I bought a retail version of half-life with no CD key, before I reinstalled windows I got the CD key from the Steam version of the game that I had bought, and that worked to activate the retail version. I found the key somewhere in the registry, now I have reset my PC, I don't know where I found it but have looked everywhere I can imagine it being but I can't find it.

I think this may be because I got the game from a bundle, perhaps this gives you a CD Key for all of the games in the bundle and if you use a CD Key, it saves it in the registry. Or maybe a key is put in the registry of all the games you buy but they get removed after reinstalling Windows.

Is there any way of activating my retail version of Half-Life without buying a key?


As per the FAQ

Valve games

Valve games purchased online through Steam do not include or require a CD Key.

You may have got it through an old hack that worked on older versions of the game, but it looks like that is no longer the case. Steam bought (Valve) games no longer come with a CD key