Only needed when the Virtual Integrator is used.
As the license is based on the N870 MAC address and the Virtual Integrator is not an N870 device, you need to define the Master DECT manager.
In the Integrator web-interface go to SETTINGS - DECT manager - Administration - Global settings
Select the Master DECT Manager.
The Master DECT manager need to be installed, connected and working as the real MAC address of this device is retrieved.