Hi,
To apply and SLF licence file to GSS just copy it into the Licenses folder in the eXpress share and thats it. You'll be licensed!
The default install should put this as this path: C:\Program Files (x86)\Altiris\eXpress\Deployment Server\Licenses
The trialware download automatically has the trial license installed so you don't actually need to do this. But it's nice to see it working anyway ;-)
Kind Regards,
Ian./