The number of ports available for an Essbase Server represents the number of licensed concurrent connections. Essbase provides one reserve port for the system administrator. A system administrator uses the reserve port to log out one or more users when all other ports are in use. See Running Essbase Servers, Applications, and Databases.
In Administration Services, a port is in use only when an Essbase Server connection is established. See “About Essbase Connections and Ports” in the Oracle Essbase Administration Services Online Help.