Hi
The licencing is always changing so if anyone else knows better please pipe in, the last client (About 2 years ago) that we upgraded after they had lapsed on their annual maintenance had two options:
Buy a complete new NAV licence as a new customer
Or pay the outstanding amount for all the years maintenance that they had missed then a penalty for not keeping it up to date
In our case they went with the catch up and penalty
Hope this helps
Nev