The following are key “end of support” dates for Windows 7-10 product releases.  Windows 10 version 1511 end of support occurs this month

https://support.microsoft.com/en-us/help/13853/windows-lifecycle-fact-sheet

Every Windows product has a lifecycle. The lifecycle begins when a product is released and ends when it’s no longer supported. Knowing key dates in this lifecycle helps you make informed decisions about when to upgrade or make other changes to your software. Below are the end dates for Windows lifecycle support:

WINDOWS 7 — END OF SUPPORT DATES
Windows 7 Gold …………. January 13, 2015
Windows 7 SP1 ………….. January 14, 2020

WINDOWS 8 — END OF SUPPORT DATES
Windows 8 Gold …………  January 9, 2018
Windows 8.1 ……………. January 10, 2023

WINDOWS 10 — END OF SUPPORT DATES
Windows 10 v1507 ……….. May 9, 2017
Windows 10 v1511 ……….. October 10, 2017
Windows 10 v1607 ……….. March 2018
Windows 10 v1703 ……….. September 2018