USG 40 - Extension for SSL VPN

Hi,

we're using a USG 40 to access our office from remote location.

We've set up L2TP connection but it's totally not reliable as almost every time a user reboot it's computer (all Win 10 machine) it doesn't work and it gives error 789.

So I want to switch to SSLVPN as it's more stable and works like a charm but noticed that our USG has only 5 free slots. My question is: is this the right code we have to buy in order to extend SSL VPN capacity to it's maximum?

The license code I've find is this:

LIC-SSL-ZZ0016F

LIC-SSL, SSL VPN License add 10 Tunnels for Unified Security Gateway and VPN Firewall

Is this the right code?

Thank you

Kind regards

Kari