vpn-session-timeout <time> <<- this command under the group-policy will end the session after specific time
Configure a maximum amount of time for VPN connections, using the vpn-session-timeout command in group-policy configuration mode or in username configuration mode.
hostname(config-group-policy)# vpn-session-timeout {minutes | none}
hostname(config-group-policy)#
The minimum time is 1 minute, and the maximum time is 35791394 minutes. There is no default value. At the end of this period of time, the ASA terminates the connection.