desktop 10.3.2 MP 10 Windows 10

I have been using PGP Desktop 10.2.0 freeware version on Windows 7 (I got it to use as demo and exercises for my students).  Now I want to upgrade to Windows 10 and am told that I need PGP Desktop 10.3.2 MP10.  Since I have been using the (crippled) freeware version, I don't have a license.  How can I continue to use PGP Desktop (crippled) in the same way.  If I do need10.3.2 MP10, where can I get it?