External connector

Hi Guys 
I have the granule 2510 - External Connector licensed, I have some Nav web services configured and working (NAV 2009 SP1/SQL 2005)
I’m Providing customer ledgers entry information’s to my Customers, but I still have the consumption of Full user licenses and sometimes I run out of licenses because the customer use a lot of connections.
Can someone explain what is needed to make the unlimited user access like Microsoft sell us?

Thanks in advance