Answer:
No matter how little or how much you use me, you change me every month.
In marble halls as white as milk, lined with a skin as soft as silk. Within a fountain crystal-clear. A golden apple doth appear. No doors there are to this stronghold, yet thieves break in and steal the gold.
When does Christmas come before Thanksgiving?
What has 3 feet but cannot walk?
What instrument can make any sound and be heart, but not touched or seen?
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.