Best way to reinstall Windows 10 on SSD? (W8 upgrade)

[ps2cho]

So a copy of windows 10 I have was based on the Windows 8 upgrade and thus I'm unsure of what my product key is...

...what my best choice is to be able to reinstall onto a new SSD.?

Anybody know how to deal with this?

 

[EarthDog]

Do you have a MS account? Isn't it stored there and when you log in it should have that on record.

 

[JLK03F150]

I have a PC with Win8 to Win10 upgrade. After a HDD failure, I downloaded Win10 to a thumb drive on another PC & installed to the new drive on the upgrade PC. It never asked for a key, it just activated. That was a year ago, don't know if anything has changed with that process.