I am not from Laminar Research; just a flight simmer from downunder.
I cannot give you a definative answer however I make a few observations.
Have you been using the software and applied the product key? If so I would suggest your Mac version with the product key is now registered. In addition when you downloaded the installer file you were asked for your operating system. In your case it was a Mac. Mac does not install in the same manner as a windows version.
Considering my comment above my thoughts are that in converting to a windows based system you will have to purchase the software again with a new product key.
Before you make the purchase I would suggest you contact Laminar direct at firstname.lastname@example.org for a definative answer.