Gabriel Aul, General Manager for Operating System Group's Data and Fundamentals Team at Microsoft, said that Windows 10 Insider Preview users will only retain genuine and activated Windows 10 copies if they opt-in for future pre-release updates on either the Fast or Slow cycle. Users will need to continue updating to the latest preview build, or have the pre-release software licence of their build expire.
If users decide to opt-out of the updates, their builds will no longer be "activated under the terms of the Windows Insider Program", and they will be eligible for the same free upgrade offer as genuine Windows 7 and Windows 8.1 users, while new users (including those coming in from Windows XP or Windows Vista) will have the paid upgrade path.
In other words, if you opt out of the Windows Insider program, you will no longer have a licensed Windows 10 copy.
Aul says in the blog, "Let me start by restating very clearly that Windows 10, whether you get it on 7/29 or whether you got it in a preview form through the Windows Insider Program is intended to be installed on Genuine Windows devices... This is not a path to attain a license for Windows XP or Windows Vista systems."He adds, "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."