The membrane can protect the LCD screen by preventing it from your sweat and unconscious stroke and touching of your nose when you use the camera. These actions are not benefit for the protection of the screen.
There is no need to stick membrane on the lens of the camera. The surface of lens itself has coating which can be corroded by the membrane stuck by ourselves. To protect the lens from scratching and touching, it's recommended to buy an ultraviolet filter with multilayer coating which can resist ultraviolet light and prevent the amount of light from dropping at the same time.
