Answer:
One simple click, one simple flash. A piece of memory, for years I'll last. What am I?
I eat I live.I breathe I live. I drink I die.
I am a mountain at night, meadow at day. What am I?
What goes up and down stairs without moving?
I am Invisible Man's drink at snack time
No matter how little or how much you use me, you change me every month.