A light's range property determines the distance, in world space, at which meshes in a scene no longer receive light emitted by that object.
There are maybe many lights in a scene, but at
most only 8 lights can be actived for realtime lighting at one time. So must
pick out most important lights before every frame rendering: for surface &
terrain, it's determined by the distance from light to camera, the light nearer
to camera is more important; for static mesh & mobile, it's determined by the
distance from light to mesh. This picking algorithm does not take light's range
property into account by default; but there is a console variable 'r_check_light_range',
if it's nonzero, then if the distance > light.range, the light will be excluded.
The console variable is useful when you use light in shader (like dot3 shaders), turn on the variable, the light which out of range will not set to shader.