The only link I provided is talking about something that looks like a store to me and is not kinguin.
All provided examples are for "not working" keys. That's kinda scum and the problem of people buying things without money back guarantee.
More important they are talking about windows 7 which had to be activated with key on every install. With windows 10, the activation is tied to particular HW/user and the key is not required to activate windows on the reinstall on the same machine.
I never had an issue with activated windows. TBH, I don't remember hearing about someone with "revoked" activation".
As for numbers of licenses, I worked in a company that was buying workstations that arrived with license. The IT would simply flash a...