From FileMaker's Licence FAQ:
Am I allowed to use FileMaker software that I've licensed on my computer at work on my home or portable computer?
In order to provide our customers with the flexibility to take their work home with them, we provide limited home/portable use rights for FileMaker Pro software. As long as you are the primary user of the computer at work, you may make a second copy of FileMaker software for your exclusive use on either a home or portable computer. Note that you may only make one such additional copy for either your home or portable computer, but not both. And only you, and no one else, may use the copy of the FileMaker software installed on such second computer. Please note that these rights do not apply to students if the software is part of a volume license program ordered at an education discount. Further, these rights do not apply to FileMaker Server software.
Reading the above, I would consider installing FileMaker on your desktop PC (windows) and MacBook Pro (OS) as perfectly acceptable. (Unless I am reading it entirely incorrectly )
When you purchase FMP or FMPA it comes with PC and MAC version. If you buy digital download remember to download both versions. You can install on both computers, but you can only use one copy at a time. You will have to purchase additional license if you want to use both versions at the same time or network.
License agreement :
It states install and use one copy at a time. I don't remember the install being part of the license agreement. I believe the main idea here is that you are the only user using the copy and you are only using one copy at a time. It would be a headache to install then uninstall to do testing and create a runtime on the other platform.