Hi Dave
My understanding is 'Per Seat' licensing is actually now called 'per device', and that means that each and every device connecting to SQL Server MUST have a license (CAL).
Even when using a middle aggregrator, such as a web server, each ultimate client MUST be properly licensed. Every client using the web server, or other middle aggregrator, MUST have a CAL.
A single properly licensed client can have multiple connections.
How many users/devices do you have currently accessing the Exact databases? Exact in EMEA do sell SQL licenses per CAL and also per Processor so you need to see which option fits best for you.
Hope this helps