the only thing i can think of is... once u turn on your internet connection win10 send telemetry to MS and activates the OS.
Let me ask you this way: (As previously on this forum I read something like you have to export a HTML or XML file, and that is your key. something like that.) So, I have this blank machine, I installed 7 onto it, activated with the help of Daz, upgraded to 10, done. Now, for example, I need this piece of hardware to be blank again, so I can install Linux onto it, as its some OS to the main hard drive, previously can I export a key of any kind from 10, to be able to reinstall it to the same machine as the main OS, some time in the future, long after any July 29 or even extended deadline passes. I hope, it's understandable, my question. Is there such a key I can get onto a USB drive, or text file... anything?
I have the feeling we're on a ever repeating Q & A After establishing the HWID by upgrading once on the pc, that HWID will be stored at MSFT servers and can be re-used whenever you want on the original pc for the lifetime of it's hardware (at reinstalling just skip the key questions). And when you link the HWID to a MSA it will even be transferrable to another system or the MSA can be used to troubleshoot/fix the activation when the HWID is not valid anymore for any reason.
Ah! Okay, okay, I have connected the dots! I need to connect HWID to Microsoft account, gotcha! Separately - I read here before about how you can work with Windows 10 USB ISO images, something like that. That only on later, subsequent re-installs, or, on the first install as well? Which topic covers my situation, if any? - THE US and EU version thing is still a mystery for me. If I want the EU version in Windows 10, do I need to upgrade from an EU Windows 7, or can I upgrade from a US Windows 7 as well? Ideally, I would prefer a US English speaking, but EU version Windows 10. Which ISO image (code) is for me? - Or, the HWID and MS Account is valid for both the US and EU versions, on a later reinstall?
But doesn't make much sense to me, as I could install with original language and afterwards install LP. (pro etc.) ProductKeys are indipendent. Buying from store should/would be independent (just guessing).
For as long as i install systems, keys were not language dependent, neither is this new HWID method. It hashes your hardware and links it to the os it got hashed on. You also can establish multi HWID's like for Home and pro and the N versions too.