I'm running FL12 64bit and have downloaded 3 demo plugins from Waves, the J73, abbey road vinyl and api2500.
I have installed them with Waves central. I see in the application that the licenses are installed on my PC ...
FLStudio 12's demo to my Windows 8.1 laptop, I set up installation so that the FLStudio 12 folder will sit PC < C: (Windows) < Program Files (x86) < Image-Line, and VST files in Program Files ...