Did you install Windows 10 directly or did you install some previous Windows version and then upgrade to Windows 10?
If you used the upgrade path (which I did), then you will need a new license. Upgrades are tied to the hardware on which they are installed. Change the hardware and you need a new license (in my case, I had to reinstall Windows, but this was because I had no additional Windows 10 licenses and had to use yet another license from a previous Windows version).
If you used a Windows 10 license, provided that you (at least once) logged into a Microsoft account using the previous KY NUC, the licensing should be ok. Simply install the SSD(s) and SODIMM(s) into the new unit and boot. Once you log into the account, if it doesn't reactivate automatically (since I didn't go through this myself, I am unsure about this part), you can simply reactivate it yourself (you aren't supposed to have to reenter the original license key, but have it handy just in case).
Hope this helps,
Thank you for the detailed answer. That was very kind of you. I did install Windows 10 directly (not an upgrade). I might have a problem with "provided that you (at least once) logged into a Microsoft account using the previous KY NUC," since I set up the NUC with a local account, don't use any of the apps from the app store, don't use Cortana, have telemetry shut down, and am currently wearing a tinfoil hat (just kidding about the hat, actually). We'll see I guess!
Should everything else -- drivers, etc -- work in the new NUC when I install the old SSD in it? If there is any reason why it would be better or cleaner to wipe the SSD and start over, I'm willing to do that.
I am much the same. I will not use any of MS' spyware-filled Metro crap. As for their new browser, it won't work on local accounts, so snooze they lose. I love their "let's delete Paint so the average idiot will use our spyware-enabled Paint 3D". Forget it; they can take their scummy store and... Well dang, you got me going there. Let's just skip to where I say that this is somewhat problematic. You may need to use another key as only through login to one of their accounts will they actually save the digital key. Still, try to get it going and see. Just don't get your hopes up...
Ah, thankfully there are 3rd party apps for nearly everything, or desktop versions. I was even able to re-activate Windows Photo Viewer and set it as default so I don't have to launch the Photos app. It seems like we go to a lot of trouble to make make Windows 10 behave like something other than what it is.
Thanks again for the assistance!