License of a "Tool" from Marketplace

Hi, there is an awesome tool on the marketplace - FluidNinja VFX Tools in Visual Effects - UE Marketplace

But I’m confused about licensing. So, the author is ok with selling the output textures, because they are actually my intellectual property. But, is the standard UE4 license applied? I’m talking about 5% royalties. Also, am I allowed to sell the generated outputs anywhere, on Unity/Cubebrush and etc.?