Are the codes from a computer game that I installed somewhere in the computer?

I recently made a big move. I had to downsize a lot, so I stupidly left all the boxes to my games where I moved from. As you know, in order for you to install the game to the computer, you need the code from the box or paper or whatever. Well, I don't have those, so are they somewhere in the games files on my other computer? Because, now I have my own, and I have to get my games on mine, so that I can delete them from my moms computer.Are the codes from a computer game that I installed somewhere in the computer?
Well, not exactly. If the game's already installed, there are key finders (Jelly Bean? I think that was the name) that will extract the name out of the already installed game. I know they're on Majorgeeks.com