Which versions can be upgraded for free for win10

First, win10 free upgrade support range

Windows10 official version for Win7 SP1, Win8.1 users to provide free upgrade service within one year, but need to pay attention to Win10 for qualified Win7SP1/Win8.1 Update/Win10 The preview version offers a free upgrade. Win8 needs to be upgraded to Win8.1 for free through the app store. The rest of the version will be automatically updated to keep it up to date. In addition, the Win10 free upgrade is only for individual users, and enterprise customers still need to obtain Win10 license through SA (Software Assurance Program).
In other words, Win7/Win8/Win8.1 volume license users do not enjoy this free upgrade Win10 activity. It should be noted that Win7/Win8/Win8.1 Enterprise Edition is a volume license version and is not included in this upgrade. The remaining versions can be identified as follows:
Win+R” Shortcuts open & ldquo; Run & rdquo; window, enter "slmgr.vbs /dlv", note the third line of content in the pop-up window "Windows(R) Operating System, ********* channel”, the asterisk part of it represents your system key type, if you prompt VOLUME, this free upgrade activity is not supported.
Windows Phone, Microsoft will provide Windows Phone 8.1 for Windows 10 mobile version (ie Windows10 for phones) free upgrade, and WP8 needs to upgrade to WP8.1 before the next upgrade.
As for Windows RT, do not enjoy this free upgrade.
Second, win10 upgrade method

Microsoft will provide system upgrades by providing ISO image and Windows Update.
Win7 SP1 and Win8.1 With Update users can choose to use an ISO image or upgrade directly to Win10 via Windows Update. The remaining Windows versions must be upgraded using ISO.
WP8.1 needs to be upgraded to Win10 mobile version through Windows Update, and the remaining WP versions cannot be upgraded.
Can non-genuine Microsoft systems upgrade win10?
Terry Myerson, vice president of Microsoft operating system, gave an explanation in an interview with Reuters: as long as the minimum requirements for hardware configuration are met, whether it is non-genuine or genuine Windows can be upgraded to Windows 10. A Microsoft spokesperson added that users who use non-genuine Windows systems are still non-genuine after the upgrade. Microsoft will provide mechanisms in the Windows 10 app store to help users buy and convert to genuine.
Specifically, this Win10 global upgrade policy will adopt a free upgrade, genuine activation strategy. That is, all versions can upgrade Win10 for free. The verification will be completed after the Win10 installation is completed, and the genuine Win8.1/Win8/Win7 in the free upgrade scope will be activated. It should be noted that users who have upgraded through Tencent or 360, more relevant information and specific upgrade terms will be provided by third parties.