SOAPSESSION=1 effect on licensing

Hi,

In an Ensemble message bus that has a Business Service which extends EnsLib.SOAP.Service, I have the option to support SOAP Sessions by setting the parameter SOAPSESSION=1.

The comments says this also effects license consumption.

In what way  is license consumption effected ?

note this is version 2015.1, Ensemble Elite (without Web-AddOn).

thanks - 

Steve