Internal Simulator Royalties

I apologize if this has been answered already. My question relates to the use of Unreal Engine 4 for the development of a simulator that is not sold but only used internally by a company. For example, this company could be a drone manufacturer. They may want to test out some of their auto-pilot algorithms in a simulator before modifying the code of the auto-pilot module the drones are using. If they develop this simulator with UE4 and use it internally for testing only, would they have to pay any royalties or fees to Epic?

No royalties are owed for internal-only use (i.e., where there is no revenue). Note that the following are prohibited uses:

aircraft navigation, aircraft communication systems or air traffic control machines, or for military use in connection with live combat

Thanks for the response. To clarify, would a flight simulator be prohibited if only used for manufacturing purposes? The drones would be sold commercially.

I understand a flight simulator to simulate rather than achieve flight, so that wouldn’t trip over the prohibited uses language.