I know the UDK has been discontinued, and is a bit “old-fashioned” compared to unreal engine; but still, it’s a great tool for creating games.
My question is whether I can use unreal marketplace assets in the UDK, (in this case models, sounds, textures, etc.) whether they are free or purchased by myself.
Is this procedure allowed, within the terms of use and licensing of both engines, or would I be violating any rule stipulated by epic games, if I did that?
You are allowed to use any paid for assets in any other engine, if they were free they are only allowed to be used in Unreal Engine.