I noticed that Microsoft have closed the Insider from being downloaded. What happens if I install my downloaded build on a new PC?
You can't activate it. All keys have been disabled.
So I can never format?
Michael this isn't true at all, the insider keys still function and will activate a 30 day trial on the newest ISO. If you're machine was activated before you install the newest build then you're build will be activated and if you're computer came with Windows 8.1 then it will pull the keys from bios.