Does a mesh need UV if there is no texture? To be more specific, I'm making a glass table that consists of two parts: the legs part, which has a metallic material, and the glass top, which has a glass material. Do I have to UV unwrap them, or it's pointless if there is no texture applied to them? 

As I know, if I want to import it to a game engine, they need at least one UV map for the lightmap. Though I'm not sure. 

So please tell me if I need them or not.
Thank you
You don't need to UV unwrap the mesh if you can use the procedural texture coordinates like Generated or Object to get the material you want. This applies mainly to within Blender. If you are exporting to another app, like a game engine, you'll need to use the most compatible texture coordinate mode, which may in fact, be UV.