Inquiry on CMS IntelliCAD 12.0 PE Plus Network installation

Our company just acquired CMS IntelliCAD 12.0 PE Plus Network - 3 Concurrent Users. I'm having a bit of trouble understanding how to make the license work on 3 separate PC's.
I managed to install it on 2 PC's of the 3 connected to our network but I had to enter the activation key both times, the PDF states that activating the license at one of the clients is enough but it didn't work for me. The 2 initial PC's still run Intellicad and don't show the 15 day trial pop-up. The third PC I tried it on won't activate the license even with the key... Did I miss a step? Do I have to uninstall and try again from scratch?
Also I think I missused NKLS since I installed it twice.. on the second PC as well as the first. Maybe this is the root of the problem.
Could I get a detailed explanation?
Thank you.