Answer:
What pulls you down and never lets go?
What goes up and down but never moves?
You use it between your head and your toes, the more it works the thinner it grows. What is it?
Its days are numbered.
Lovely and round, I shine with pale light, Grown in the darkness, a ladyβs delight.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?