As far as I know, Macs are infintely better than Windows PCs
But yea, Mac/Windows licenses are interchangeable. Linux, however, is not. If you want to play on both, just copy your .lg file from computer to computer by flash drive or an online service, or just keep your game on a Mac and Windows compatible (some require you to reformat for use with the other) and plug it in when you want to play.