Can Firebird be used by multiple network users without breaking Microsoft Windows license?
Short answer: Yes
This depends on the network protocol you use to access Firebird database. Each NetBEUI (Named Pipes) connection uses file access via Windows networking (pipe is a type of file) and requires Windows license. Those connections have a connection string like this:
However, if you use TCP/IP you can serve unlimited number of clients as it is not restricted by any license. Since TCP/IP is more common and preferred way of accessing the server, we can conclude that this isn't really an issue with Firebird: you can have as many clients as you want. TCP/IP connections have a connection string like this: