I'm wondering what is the best license for our environment.  We have 1 developer doing the development and testing on his localhost.  We will then deploy the web application to one server which has 3 different sites.  Example : http://servername/site1... http://servername/site2...

Yes you answered my question fine.  Since all three are currently on the same domain we could use the IP license.  Does it matter if the three websites are on different ports 80, 81 and 82?  Also,  if another developer needed to be added to the project what kind of license would that require?