Windows 10 upgrade stuck to pc?

[Hasher]

I'm building a new PC and i was wondering if the windows 10 upgrade is stuck to your pc or you could keep your old system on windows 8 and upgrade to 10 on the new build?

(A fools hope i know but i just want to be sure)

 

[USAFRet]

You can't use the original 8.1 AND the Upgrade to 10 at the same time. They are not giving you a second OS for free.

 

[JackNaylorPE]

It's an upgrade .... not a new OS. The license is tied to the box you are upgrading from.