Swapping Drives

I have several pc's here that are some used regularly and some for spare components such as memory or drives.
Recently an 8.1 Acer I used regularly died with no boot device recognized. Intell j1900 processor. Nothing special but suited my needs and use. I had 2 offline 7 machines. One a EMachines was mostly just like this Acer. Same style, same size, layout inside mostly the same. The hard drive and dvd rack and placement was almost exact. However it is an AMD processor with the ATI graphics.
I have images of my 8.1 and several hdd's I could select from to replace the drive while I work on recovering the one gone bad. Have several boot discs/ usbs to try to work on it.
I took the hdd/dvd rack out and swapped it into the Acer.
It booted straight away. I had already taken the mb out of secure boot to try a couple usb's so legacy was in effect. There was a pop-up about ATI catylasy control not being compatible with this video card. Also it did not recognize my wireless, a wnda1400. I went to a Win10 online to get a driver and after a half hour, I never made it past the first click on the netgeardotcom page using Edge and the machine's built in wireless.I couldn't find my cd with the netgenie and driver install programs. So my choice was the next day to buy a new dongle with an install cd. Prices have sure gone down!
Once I got the wireless going, I headed to MG's home page and decided to try out the IOBit Drivr Booster FREE. It found several devices that were showing errors in Device Manager. It even showed the wnda wireless driver as missing. Had an update listed for the j1900 proc. Also showed the drivers missing for an ethernet controller, pci encryption, universal usb controller, and several audio, video and game controllers. And one for the Intel HD Graphics.
I was left with only one unknown device, a IUSB3 root hub. I have my mouse plugged into what I think is the usb3 and it works okay.
All the simple 3d games I play work, once I was able to uninstall the ATI conrol program and the Intel HD Graphics kicked in.
Now I know what some of you are thinking.......... license.............
I thought about that too. Well, my 8.1 disk was laying on the floor and the '7 machine doesn't have a power supply, so I figured I'm still only using one product on one machine. But not the original machine........and Windows was counting down 28, 27, 26....days till activision.
I tried the links listed on the System page in Control Panel, but all lead to a Win 10 product page. I searched and wound up on a MS forum page long ago closed but still listed. I kept seeing "enter product key off of label".......... So i looked at the label, entered the code and after a few minutes it activated.!!
SO, am I legal? Bootleg? Gray area?...........
But I did learn you can take a drive for a different pc and still get it to work okay.
And not too hard.