Even if they did, art assets (meshes, textures, and often animations) generally are very easily transferable. I don't think the Unreal Engine marketplace licens

Even if they did, art assets (meshes, textures, and often animations) generally are very easily transferable. I don't think the Unreal Engine marketplace licensing says anything about not being able to use commercially with a different engine. Could be wrong, but when I checked a few years ago that was my impression