It seems there’s some good answers on here already, but I can add a little more.
The basic difference between PaperCut NG and PaperCut MF is that NG will track any network printer on a PaperCut controlled print server, whereas MF extends the NG functions to also include your copy/fax/scan/print release style services at the MFD.
For NG, licensing is based on the number of users. MF is users and MFDs you would like to control for copy/fax/scan/print release on. There are *some*exceptions to this (connectors to PayPal or other online payment systems comes to mind) but not many.
You’re welcome to use the NG trial to experiment, Download - PaperCut NG - PaperCut or we can put you in touch with a PaperCut reseller.