Microsoft has confirmed that the hundreds of thousands of people who have enrolled in the Windows Insider programme will get a free copy of Windows 10 when it goes live.
Gabriel Aul, who is one of Microsoft's main spokespeople on Twitter, took to the social network to reveal that Windows 10 RTM will be free to Insider Preview users.
RTM (release to manufacturing) refers to the stage where Windows 10 is considered ready for mass distribution – the latest (and eighth) iteration is Build 10074, widely considered to be what is traditionally known as the beta version.
Microsoft already confirmed that Windows 10 will be free for Windows 7 and Windows 8.1 users, so in theory, a Windows Vista user could install the current Windows 10 Preview and upgrade to the final version when it is launched later this year.
What Aul hasn't said, though, is how Microsoft plans to limit and control the number of installs and how the licenses are transferred/managed post-installation.
(ed: Aul subsequently confirmed on Twitter that only those with a genuine, valid Windows 8.1 or Windows 7 license would be able to get Windows 10 for free).
What would, for example, prevent someone from downloading Windows 10 on 10 different, antiquated PCs, and then transfer those (or worse, illegally sell them) to a third-party down the line?