cookie expire time

You should be seeing the total_active_clients number decrement on each close connection. If someone closes their browser you should eventually get a session closed.

Regardless, though, the answer to your question is yes, you can absolutely set and check the cookie expire time:

 
 HTTP::cookie expires  [seconds] [absolute | relative] 
 

The above link that cmbhatt posted has all of the HTTP::cookie commands and their syntax.

Hope this helps,

Colin