Upgrading Windows 10 Home to Pro with Windows 7 pro license?

I apology if this was asked already but I cannot find related question.

So thing is I have legal Windows 7 Home license and I have upgraded this machine to Windows 10 and it is up-to-date. However, two out of four RAM modules, or buses, are not functioning at all, so I was running with 4 GB ram for like half year. Untill today.

My father's company had some left over desktops with pretty good stuff in them. So as my motherboard only supported 8GB RAM, I decided to take new motherboard (alongside with new i7 CPU and 16GB RAM) from one of the desktops, not touching the hard drive. I installed everything on their places and I was booting up my computer just fine untill it tried to get on the login screen.

I was wondering why does it take so long to get on the login screen, but then I realized that when you switch motherboards, the old drivers cannot obviously be found. I started to "panic" a little and googled around to see what to do. But luckily, after two automatic reboots, it got eventually on the login screen and I was able to login. First I was wondering why all the shortcuts on my desktop are missing (Well I have only 4 of them so not a big deal to add them back) and then I tried to check if Windows Update had found any updates to these new drivers.

I found out that Windows is not activated. I used ProduKey to find out my Windows 7 Home product key since there was no sticker anywhere but it was unable to verify it (yes I realized it's verified to the old motherboard). But luckily again this leftover desktop had the sticker on the case with valid product key. I entered it and it was verified, but then the activator told me to change to Pro version. When I pressed cancel to that, it didn't activate.

So my question is what happens when I upgrade to Pro version. Will this Windows 7 Pro product key work? Does the upgrade remove programs/files (I don't have my backup hdd currently here...)? If everything would go fine, can I forget I have ever had Home version (and can I forget the Home product key as well)?

And sorry for quite long post and sorry for my English too. It's not my native language.

I searched from internet for quite some time and I decided to do the upgrade.

I entered the Windows 7 Pro production key again and accepted to do the version upgrade. It did the upgrade quite fast and it actually activated Windows.

Please note: this Windows 7 Pro production key was NEVER even upgraded to Windows 10, and I was still able to upgrade my Windows 10 Home to Windows 10 Pro with it. So everything is fine, the upgrade did not touch any programs / files (as matter of fact it only implented the Professional features).

Conclusion: I got 16GB RAM, better motherboard, better CPU, and upgradation to Windows 10 Professional, for free. I think it could not have gone any better?