Ok a bit of an oddity this one. About 6 months ago I aquired an i5 laptop ... Acer Aspire. Nothing special. It has no OS and the hard drive had been wiped. I did nothing with it until the first insider preview was released for Windows 10. Since then I've had multiple Windows 10 previews on it, both from updating and fresh install from ISO. It updated to build 10240 like all others and remained activated on Pro. I decided to take a look at it today with a view to installing Windows 7 for the first time on it and upgrading to 10 to get permenent activation. But before I did I curiously ran slmgr /xpr and it reported that it was permenently activated. Odd ... so I took the Win10 DVD and did a fresh install, wiping the HDD out. I chose Pro and skipped the cd key (both times). It connected to the internet and activated ... so it's activation really is permenent. The question I have is WHY? I didn't upgrade from Win7, and the Win7 that came with it was Home Premium so I would normally only be eligeble to upgrade to Home, not Pro like I have. So M$ have just given me a free Pro license for this PC for running the insider previews?