Hi,
The UE4 EULA (EULA - Unreal Engine) says this about use restrictions:
You may not engage in any activity with respect to the Licensed Technology, including as incorporated into a Product, (1) for any gambling-related activities or Products (as defined by law in the jurisdiction of use); (2) for operation of nuclear facilities, aircraft navigation, aircraft communication systems or air traffic control machines, or for military use in connection with live combat; (3) in violation of any applicable law or regulation; (4) in which the Licensed Technology is rented or leased; (5) that misappropriates any of Epic’s other products or services; (6) in support of a claim by you or any third party that the Licensed Technology infringes a patent. You also may not sell or grant a security interest in the Licensed Technology.
Best,
-j