The Cisco Asa can be loaded with an AnyConnect Essentials bundle to handle to maximum number of sessions supported by your ASA appliance. But even though you have applied the Any Connect Essential bundel you still find the device limited by two sessions.
When you check your logging you will see the following two notifications:
%ASA-4-716023: Group <GroupPolicy_VPNUSERS> User <user> IP <IP> Session could not be established: session limit of 2 reached. %ASA-4-716007: Group <GroupPolicy_VPNUSERS> User <user> IP <IP> WebVPN Unable to create session.
Check your firewall version to see if the AnyConnection license is applied.
show version | grep AnyConnect
AnyConnect for Mobile : Disabled AnyConnect for Linksys phone : Disabled AnyConnect Essentials : Enabled
Check you Firewall configuration to see if the AnyConnect is enabled
show run | grep anyconnect-essentials
If you receive zero results you have to enable AnyConnect-Essentials on the webvpn
Config t webvpn anyconnect-essentials
This will enable the AnyConnect-essentials.
This setting can be set in the ASDM as well:
Configuration, Remote Access VPN, Network (Client) Access, Advanced, AnyConnect Essentials.
Select Enable AnyConnect-Essentials.
Now you should be able to connect with more than two users.