"For one Mac" is the legal phraseology in the license agreement....it simply means that Microsoft doesn't want to allow you to use their software on multiple computers. It implies that you will need to buy a new license if you change computers, but that was not my experience when I migrated to my new computer. The new me still had a functional Office suite while the old me retained functionality as well.....legally, I did the right thing by removing Office 2016 from my prior MBP before passing it to its' new owner.
When I got my new MBP I had forgotten that my Office 2011 was "For One Mac Only", so I didn't uninstall it from my old one, but, same as you, I was able to install it all the same. (My old MBP went back to Apple, so my having failed to uninstall it was legally inconsequential.)
