Insider Preview users won't need to reserve their free upgrade to Windows 10 RTM
You can upgrade to the final build when it becomes available
on Saturday, Jun 13th, 2015 at 10:11AM @ronwinbeta
One of the big questions regarding Windows 10 has to do with acquiring the free upgrade from Windows 7 or Windows 8. Microsoft announced not too long ago that you can reserve your free upgrade to Windows 10 within a year of its launch. However, for those of you already on the Windows 10 Insider Preview program, you will not be required to reserve your free upgrade. Instead, your free upgrade will be available to you once the final build is released. Windows 10 is set to be released on July 29th.
"You won't need to reserve, and if you're running Insider Preview you'll be upgraded," Microsoft's Gabriel Aul stated. Microsoft is already allowing users the ability to reserve their free upgrade during the initial setup process of Windows 8.1. This means that new users who recently purchased a Windows 8.1 device simply can't miss the chance to reserve Windows 10. This also appears if you clean install Windows 8.1 with November Update roll-up and are connected to the internet.