Hello,
probably there was some problem for the installer to acquire administrator rights during installation. You should be able to fix it by running the "c:\NXP\FreeMASTER 3.1\FreeMASTER\register.bat" as administrator.
If this does not help, please re-install the FreeMASTER. First un-install the product and then install again by running the installer "as administrator".

Regards,
Michal