It seems the trial download is the old build that didn't want to start a trial on all systems.
To fix that create the following folder :
c:\programdata is hidden by default but if you press winkey + R to open the run dialog you should be able to type c:\programdata and press enter and it will open the folder. Then create th Stardock folder and then the Registrations folder inside that.
Then start WindowFX again and the trial should start fine.