One software license is required per user.

Single-User License.
The Single User License allows a single copy of software program to be installed and used with only one person on one computer. If other users will use the application on any of the computers that the application will be installed on, then additional Single User Licenses or a Network License needs to be obtained for each user who plans to use the application.

Server - Concurrent License.
The Concurrent license is a server license based on the number of simultaneous users accessing the program. It typically deals with software running in the server where users connect via the network. For example, in a five-user concurrent user license, after five users are logged on to the program, the sixth user is prohibited. When any one of the first five log out, the next person can log in. Concurrent licensing can be managed by the independent software metering tools, typically running Citrix XenApp.