What is the code bound to?

I installed the game and all the DLC, and through a strange process activated it (as all DLC glitched during the installation, yet were still loaded into the game, I had to access one of the DLC places, Alt-Tab out to the window that pops up and activate, hmm...), but now I wonder... what is it attached to?

I mean... there is no account to sign up to (I didn't even make an online account), Securom merely makes sure the disk is still in the drive, and the code paper clearly states that this is a one-time use.

If I need to reinstall the game, how will it 'figure out' I already put the code in? Or did they really go -that way-, as in 'if the game files are lost, you're screwed, see ya'?

I'm wondering the same thing.
Is the code a one time use, or is it simply a code that you use whenever you need to?
Like say for example that my PC or hard drive screws up & I need to get a new one. Do I just use the same code?