On Wednesday, November 14, 2018 at 3:55:33 AM UTC+8, Paul wrote:

If you never paid for Windows 10, then the following
"generic, useless" license keys are provided. I'm quite used
to seeing 3V66T for example. If you enter these in a license
key box, the OS will laugh at you. That's because all the
upgrade machines (7,8.1==10) use these. If you *buy*
a license, then you get a unique key.

VK7JG-NPHTM-C97JM-9MPGT-3V66T (Windows 10 Professional)
YTMG3-N6DKC-DKB77-7M9GH-8HVX7 (Windows 10 Home - multi language)
BT79Q-G7N6G-PGBYW-4YWX6-6F4BT (Windows 10 Home - single language)


Yesterday, I tried some keyfinders. One was a Lenovo, almost new, never
fiddled with.
Belarc Adviser and Licence Crawler both report a different key to what
showkey.vbs does. Belarc had a note this may be the key embedded in BIOS.

Also tried on a hard drive pulled from a fried PC. I believe it was upgraded
from Win7 to Win10.
Belarc say "key none activated" which I presume meant a digital licence.
But Licence Crawler displayed the useless default product key (3V66T)
But showkey.vbs gave a different key.