Yes, it is, as long as you have a maintenance subscription.

You can use the license with both Plug-ins but only on the same server(s) that you have the license for.

This does not apply to the JEC and EWSJ libraries. 

There is an upgrade fee for moving from JEC to EWSJ.

You can go to http://www.javaexchangeconnector.com/ for more information.