Hi - I am changing computers from PC to Macbook Air. I am a long-time PM user and currently have PM 6, build 7285 (and I think Plus, though have never used that). I want to install on my new computer, but when I enter the licence key number it says it is too short. I think I can have it on two computers, but if licence is only for one, I can deactivate on PC if need be and install on Mac only. Hope you can help! Ken Jack.