About Mobile VPN with L2TP Licensing
To support more than one Mobile VPN with L2TP connection, your Firebox must have Fireware with a Pro upgrade. The Pro upgrade is included with most Firebox models. The maximum number of supported L2TP connections varies for each Firebox model. The L2TP users value in the device feature key indicates the maximum number of Mobile VPN with L2TP connections your device supports.
VPN Tunnel Capacity and Licensing