Is the official version of win10 charged?

Win10 official version is really free?
Microsoft officially announced the latest Win10 consumer preview version, all Win7 and Win8 devices can be upgraded to Win10 system for free within one year from the release. Microsoft's benefits are only for individual users, and the free upgrade strategy does not apply to Windows 10 Enterprise.
Jim Alkove, general manager of Microsoft Security, mentioned in an article about the security of Windows 10 Enterprise Edition that Windows 7 Enterprise and Windows 8/8.1 Enterprise are not included in the Windows 10 free upgrade strategy.
Microsoft also mentioned on the official Lumia Conversation page: As with any new system upgrade process, not all devices can have a Windows 10 experience, and some new features and new features still require more powerful hardware support. And our goal is to get most Windows Phone 8/8.1 smartphones, PCs and tablets into the new Windows 10 ecosystem.