property MaxConnections: Integer;

MaxConnections is an Integer property that indicates the maximum number of simultaneous client connections allowed for the server. MaxConnections can be used to ensure that a pre-determined memory or bandwidth threshold is not exceeded. When MaxConnection is 0 (zero), the server does not impose a limit on the maximum number of client connections. 

MaxConnections is used when a TIdListenerThread for the server detects a new connection request. If the MaxConnections limit has been exceeed, the server performs its protected DoMaxConnections method, and the client connection is closed. The Abort method is called to halt execution of the listener thread.