Windows 10: NEW PC: can a bought Win 7 licence be used to upgrade to 10 or...

I am building a new PC for personal home use. I've been told I could use my laptop license for it. And elsewhere I read I can't do that. I've also read I could buy a windows 10 license key on Amazon and then use that for installation and then upgrade. But here too I found that there may be problems doing so as well. Hence, my seeking advice here.
Anyhow, I don't know who to believe or what to do. Any advice, the more the merrier, would be appreciated.

(BTW even if the retail price of Windows 10 were half its price I would have found it too expensive so imagine what I think of its current actual price. And now I am wondering if Linux is my actual only option)
The laptop was originally with a win 8.1 version which was updated free to W10 when it first came out)

Windows 10 home ver 1903 (build 18362.720)

Fun note: Back in the days when PCs were 1st introduced to the general public I was shocked to hear that the computer that I was buying would not work without an OS. I'm thinking how can you buy something if it doesn't work on its own; and why do I have to buy something else to make it work? My reasoning was, "It's like buying a radio but you can't hear any radio stations unless you buy something that makes it translate the received signals into audible audio." The PC was after all the first type of electric device where it did not function on its own. And I was surprised that nobody questioned it and just accepted it as a norm.

:)

 

Transfer Win 10 Pro Licence to a new Win 10 Home PC

I bought a Laptop with Win 7 in July 2012.

In January, 2013, I bought a Win 8 Pro licence through the promotion that was running at the time.

I have since update the original Win 7 PC, to Win 8 Pro, to Win 10 Pro and it now is running Win 10 update 1903.

I bought a new laptop with Win 10 Home this week. I will be retiring the original Laptop purchased in 2012.

Can I transfer my Win 10 Pro licence on the retired laptop to the new Laptop ?

I am getting mixed answers from the Sales people.

 

is hardware OK (Win 7) for upgrade to windows 10

I think in one of the other PC with win 7 or win 8.1 I run media creators tools and in some step prompt/found graphics card not supported... for win 10. I didn't found alone reading specs of win 10, but the tool says me... after changed graphics card the tool said all OK and continued OK with upgrade... That I ask to reach this step in this current PC - win 7 - must be all OK for the upgrade? Or must continue to upgrade to show this?
and got to point

• UPGRADE this PC now
• Create media(DVD, USB stick, ISO)

is hardware OK (Win 7) for an upgrade to windows 10 for this PC???

 

is hardware OK (Win 7) for upgrade to windows 10

I think in one of the other PC with win 7 or win 8.1 I run media creators tools and in some step prompt/found graphics card not supported... for win 10. I didn't found alone reading specs of win 10, but
the tool says me... after changed graphics card the tool says all ok and continued ok... That I ask to reach this step in this current PC - win 7 - must be all ok for the upgrade? Or must continue to upgrade to show this?

and got to point

• UPGRADE this PC now
• Create media(DVD, USB stick, ISO)

is hardware OK (Win 7) for an upgrade to windows 10 for this PC???