I'd recommend upgrading, Windows 10 is a better OS overall in my experience. The in place upgrade works very well in ever case I've tried (I'm a sysadmin so I've done a few) but I have heard some stories of problems. So make sure you are not in the middle of a project and have time to reinstall, if needed.
What I'd do, what I did in fact, is to deauthorize anything with a fussy authorization system before upgrade, then reauthorize it. So Sonar, NI Komplete, Sound Forge, that sort of thing I just left in place since they don't do deauthorization because their authorization procedure isn't silly. Melodyne, Waves, stuff like that I removed the authorization on my system and set it back to their license servers and then got it back afterwards. In terms of dongle stuff I just installed the latest drivers after upgrade and went on about my business.
Everything I left installed recognized it as the same system. The IK products didn't use up another authorization or anything.
The good news is that it isn't like you'll be the first to upgrade, literally tens of millions of people have so the companies are aware of what may happen with their particular application. Also Microsoft themselves is not ignorant of these issues and took steps to work with various copy protection vendors to make sure it'd work.
The only case I'd be concerned about is if you own a plugin that needs authorization, and the vendor is gone. Then you could lose it. Of course you are going to lose that at some point anyhow so now might be a good time to start looking for a replacement.