Poser 11 use to run under windows 7 and there is no reason to think that it won't continue to do so.  Windows 10 is the only official version of Windows supported by Microsoft so it is easier to say a program runs on the latest version that way if something does happen to Win7 then they don't have to go back and try to fix it.  Poser 11 came out sometime in 2016 I believe which was 4 years before Windows 7 EOL.  Most of the changes to Poser 11 done by Bondware were to change the owning companies server locations and some minor bug fixes.  

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13