Windows 10 version 1507 was the initial release for Windows 10, released July 29th, 2015. Use the ‘Winver’ app to read the version number. This version of Windows no longer receives security updates, and should be updated to the current Windows 10 release, or taken offline.
More at Microsoft:
https://support.microsoft.com/en-us/help/4015562/windows-10-version-1507-will-no-longer-receive-security-updates