There are 3 scenarios:
1) You want to use the PaperOffice database on the network without having to install a separate MySQL database server or install your database on a NAS. In this scenario, note that PaperOffice is running on the PC that is to act as the database server and that a user is always LOGGED ON.
For each user you need one PaperOffice user account and one database which all users can share.
Conclusion: You need 3 licenses
2) You are using PaperOffice on 2 different PCs, but you want to use a shared database, which is independent of both PC's and available all the time. For this you need a stand-alone MySQL server, which is installed on a PC or server, which is always available.
Networking is done in this case over the local network LAN
3) You want to use PaperOffice on 2 different PCs in the network and use an external, not supplied by us mySQL database, which is outside of your office.
Conclusion: You need 2 licenses and note that the external MySQL database complies with all PaperOffice requirements.
Networking over a WAN over an Internet connection. Please note that the internet connection must be fast.