One client object is created for each browser user. It is created when the user first accesses the NES application and persists until some time after they have last visited. A timeout allows the server to garbage-collect these session objects and purge them out. If a client comes back again later, a new object will need to be created.
Because there is no session object in Netscape Enterprise Server, this object serves the purpose of maintaining session state as well as holding details of the client.
To maintain state across all session in an application, you should use the project object discussed in a separate topic.
Client objects have a limited lifetime. It is configurable but typically they will expire and be discarded after 10 minutes of inactivity.