Normally, the first time you run DBP after installing a new plugin, an activation window should appear. If this does not happen, you can still activate by going to your DBP folder and run TGCOnline.exe found in the compiler folder.
Here you can see what you have activated and what not. To activate, just click on "Enter Order key" and enter your email and Darkphysics activation key.
P.S. if you lose the keys, you can still view them
here
Theory is when you know something, but it doesn't work. Practice is when something works, but you don't know why.
Programmers combine theory and practice: Nothing works and they don't know why.