I believe there was a post earlier about users experiencing issues with this, but I could not locate the thread.
So from my recent experience:
All the subscription based blades could not be licensed offline, only Firewall and IPsec VPN blades were.
Licenses and contracts were downloaded and applied via SmartUpdate, (to be precise, in R80.10 it is an executable SmartDistributor.exe).
Once cluster was brought online and the Internet connectivity was established, most blades' licenses were activated with the exception of IPS on a Standby node.
I also recall reading that for some users this was mysteriously resolved after indeterminate amount of time.
To make that interval shorter, I've failed-over from active to standby member and the licence was updated within an hour.
The message I was seeing:
Cannot fetch license information due to a configuration error. Refer to sk114615 with error ID: <7>
(Error ID 7: Could not resolve host)
Was not reflective of the actual behavior of the standby member.