I didn’t see Essentional 4 listed as being compatible with Windows 8.1, but wanted to check here in case I missed something…thanks! 
I did not install onto 8.1 but rather upgraded an already installed version of 4 from 7 to 8 and then to 8.1, and that works fine. If you have any installation problems you should install the newest elicencer software before you run the installation and try running as admin or compability mode, but once installed the program appears to run fine.