Microsoft has cleared up confusion about who is eligible for a free Windows 10 upgrade, explaining that only ‘genuine’ Windows 7, 8 and 8.1 users will be able to download the commercial final version when it is made available on July 29.

Windows Insiders have been testing preview versions of the software for a number of months, ironing out flaws and making suggestions. Microsoft says that when Windows 10 is released, insiders will have a choice of remaining in the preview programme or upgrading to the full version.

Essentially this means, anyone who doesn’t have a genuine copy of Windows 7 or 8, such as Windows XP and Vista users, will be required to stay in the Insider programme and subject to any potential bugs or flaws of preview versions if they want to continue to remain Windows 10 users.

“As part of the program we’ll upgrade Insiders to what is for all intents and purposes the same build as what other customers will get on 7/29, but that will be just another build for Insiders, and those who stay in the program will simply get the next build after as well,” said Microsoft’s Gabe Aul, who apoloigised for the confusion and said anyone who upgraded to Windows 10 would be bound to the terms and licenses of the ‘free’ update offer.

“This is not a path to attain a license for Windows XP or Windows Vista systems. If your system upgraded from a Genuine Windows 7 or Windows 8.1 license it will remain activated, but if not, you will be required to roll back to your previous OS version or acquire a new Windows 10 license. If you do not roll back or acquire a new license the build will eventually expire.

“It is our hope that the vast majority of Windows Insiders who have been with us since we announced the program last year will continue forward, and it was in that light that we authored the blog post about upcoming changes to the program. I regret that this caused confusion about who was or was not eligible for the Windows 10 upgrade offer, but hope that this helps to clarify.”