HA Active Passive Question: Does licensing need to match?

We are looking at buying a 2nd unit to act as an HA device either in Active-Passive mode or as a cold spare. 

I would prefer the HA-Active-Passive scenario, and I understand that Firmware and config need to match..however, I was wondering if the licensing (e.g. Webfilter, AV, etc..) need to match as well?

I understand that *if* this worked, it would mean that my policies and routing would all work, but my Next-Gen-FW capabilities would NOT work as I wouldn't have the passive one licensed. In this scenario, in case of failover, I'd have to follow the cold-spare process to get the license switched over after the fact.

Any info that can be provided is appreciated. Thanks