Microsoft appeared to describe a way to get Windows 10 at no cost that would apply to everyone. While the company has been clear that Windows 7 and 8 users would be able to upgrade to Windows 10 at no cost for one year after Windows 10's July 29 release, the Friday blog post seemed to create a way that everyone else could get an activated, genuine copy of the software for free, too.
Over the weekend, the company backed away from this idea, altering the wording of its post to remove the semblance of an official path to free Windows 10. Today, the company has made a third update that spells out the situation more clearly than it has done in the past.
First, it says that Windows 10, both the final release and the preview releases, should only be used on "Genuine Windows devices." Installed it into a virtual machine to test? It's probably not properly licensed. Stuck it on an old Windows Vista machine you had lying around? We don't know. Probably not licensed, because Windows Vista isn't eligible for the free Windows 10 upgrade license offer. Will anyone notice or care? No.
Beyond that, Windows 10 users are split into two camps. The first camp is made of those who want to remain in the Windows Insider program. The Insider program will continue after July 29, and Microsoft will continue to use it for beta testing and soliciting end-user feedback. Anyone who sticks with the program will continue to receive a steady series of activated, genuine operating system releases. As with any other Microsoft beta, these updates will be timebombed; after several months, they'll expire. But new versions will be provided long before those timers ever hit.
The second camp is the one that wants to opt out of the Insider program and stick with the stable release on July 29. This group will need a valid Windows 7, 8, or 10 license. Without a suitable license, the operating system will eventually expire. If the Insider builds were installed as an upgrade to Windows 7 or 8, they'll remain activated once they switch to RTM. Microsoft hasn't said what the story is if a clean installation of Windows 10 is performed; we imagine that there will be some way of entering a suitable license key to satisfy the operating system that it's suitably licensed.
Functionally, this creates a way for people to use Windows 10 forever without paying. They just have to stay in the Insider program and make sure to keep their systems updated so they never hit the expiration. But if you want a stable release build, you'll need to either have a qualifying Windows 7 or 8 license or pay for a Windows 10 license, with no backdoor route to getting one for free.