Does it use D3 Licenses?

Yes. The Web Application Server uses some D3 Licenses.

When you boot your D3 system, we take a set of licenses and hold them by starting up some phantom jobs.
This ensures we never fail to connect because all licenses are in use. This avoids any “Internet surges”
or too many employees working at the same time.

We recommend at least 2 licenses with an average of 5 for most environments.

One very large client uses 115 D3 licenses and handles 6 million subroutine calls a day with it.