Borderlands 2 DLC unlocker PC

Hey guys, i'm wondering if there is a DLC unlocker for Borderlands 2, the reason for this is because i remember in the original game, Borderlands 1, all you had to do was download the DLC and put it in the root folder of your game, and im guessing it hasn't changed for this game but i haven't gotten it to work when i downloaded it.
Is there any sort of way to get a DLC unlocker for PC?

I would love that

It doesn't work.
Believe me, I've tried.

It checks if you have it purchased, it can see it downloaded but unless it's bound to your account by purchase you can't.