Allow to run while key is removed

I am new to LDK so please bare with me if question have been answered before. 

We plan to use LDK v7.5 to Licensee a client server installation.

We will install a network license  ( with a hardware key) on a server . The clients must then request licenses from the server. 

Clients and server checks for valid license and features on startup.

Is it possible to generate a license that would allow the clients and servers to start up for a period of time (x number of days) in case that the dongle is removed from the server or due to other circumstances are unavailable?

If yes.   How should we make the license?

Best regards 

Jess Andersen