What is included in the license?

The basic license bundle is a V-Ray 3 Workstation. It includes one V-Ray Graphic User Interface (GUI) license and one V-Ray Render Node. 
The GUI license in your bundle unlocks the V-Ray menus in your 3D host platform - it enables you to use the V-Ray plugin in the host platform interface, to navigate V-Ray menus, use materials, etc. This license is not used for rendering.

The V-Ray Render Node is used when rendering - when you start a render job a V-Ray Render Node license is engaged, regardless if the rendering is initiated on your local workstation or on a remote render slave machine. In order to use more computers for rendering, you can purchase additional V-Ray Render Node 3.0 licenses (1 per machine).