The Standard NextGenSprites shaders come in 3 lighting styles; Multi, Single and Unlit.
Multi Lit Sprites are lit by Ambient, Directional Lights and Point/Spot Lights.
Point and Spot Lights are rendered per-pixel which can be costly on low-end device - try to restrict yourself on less than two Point Lights.
Furthermore, on mobile devices you should consider that even though upper-middle and high-end class mobile chipsets may handle your Point Lights quite comfortably, a high workload on the CPU and GPU will drain the battery life faster which leads in a poor user experience(and a potentially bad Marketplate rating).
Single Lit Sprites receive lighting from Ambient and Directional Lights and are rendered much faster than Multi Lit Sprites.