Distributed systems

You have four offices dotted around the country, each with an Internet connection, and you want them to use Cardbox and share their databases. What sort of licences do you need? The answer depends on one crucial question:

What do you want to happen when the Internet connections fail?

Each office works independently

In this case you need a separate licence for each office. This can be single-user if you only have one Cardbox user in each office, or multi-user of whatever size is required.

When the offices are connected, they will be sharing the same database: they will do this by connecting to a Cardbox Server at one of the offices. So your overall licensing requirement is:

Single user in each office

Four single-user Professional Edition licences, one for each office.
One Cardbox Server licence for the office where the shared databases are stored.

Multiple users in each office

Four Professional Edition licences, one for each office, multi-user (including Cardbox Server) in each case. In the office that holds the shared databases, the Cardbox Server accepts connections from all the other offices.

Nothing happens until the connections are restored

In this case, you don't need separate licences at each office.

Main office: one multi-user Professional Edition licence (including Cardbox Server), licensed for the maximum expected number of simultaneous users including those at the other offices.
Other offices: Client Edition for every user. This is available for free download.

Backup

Every office can maintain its own backup copy of the shared databases. Cardbox has a special command, Tools > Management > Download Database, to make it easy to make backup copies of databases even while they are in use.