I was under the impression Windows 10 was tied to your Windows Live account from the start.
Since launch, Windows 10 'keys' (more on that later) are either tied to an MS account, if you are signed in with one, and/or a hash of the hardware IDs of key components (drive(s), GPU, CPU, motherboard) if not. or more accurately, the key is linked to the hash, and the hash optionally linked to an MS account.
The upshot of this is, once you have installed and activated Windows on a system, any subsequent installs on the same machine will activate automatically without you ever entering a key again. This also applies if you upgrade from Windows 7 or 8: even though you are not issued a new 'key', the hash is still generated and Windows will still activate in the same way. Effectively, a Windows 'key' is now a one-time device you use for the very first install, and can then be discarded.
The rub is that if you change too much hardware (simple component swaps are not an issue, but if you swap out the CPU and motherboard and drive all at once that is rightly considered a new system), you need to to the old call-MS-and-activate dance, but that's pretty painless. Or if you have a MS account, you can skip the phone call and just log in with that account, and you will activate and update the hash.
Unless you have an OEM key. The old loophole of buying an OEM key and abusing it by swapping components and reactivating endlessly is now closed.
VOL keys need to activate against a keyserver. If you're using them at home, that means running a cracked keyserver, so definitely in dodgy territory.
