The number of concurrent VIA client is equivalent to the number of IPSEC tunnel supported by the platform and If IPsec is not available because of a firewall, the client will automatically attempt to run with IPsec encapsulated in SSL.
For a 7030 controller this would be 2,048 concurrent IPsec sessions .
The PEFV license is a per controller license, not a per user license.
Just a note, if you move to AOS8.x, the PEFV license is not supported. You would need a LIC-VIA license which is applied per user.