Do you have kbd48CNC keyboard connected to the PoKeys board? If you do, open the PoKeys plugin, go to import/export and import kbd48CNC settings from that file.
If you don't have kbd48CNC keyboard, then just delete this file.
Anyway, if you install the latest software, a new plugin is automatically installed in C:\Mach3\Plugins folder and you don't need to copy it manually. If you did copy it, install the software again to be sure you have the latest plugin.