Answer:
Everyone has me, but nobody can lose me. What am I?
The time between daylight and darkness when blood drinkers like to come out
I have no weight but I could destroy a mansion. What am I?
What comes once in a minute twice in a moment but never in a thousand years?
I take off my clothes when you put on your clothes. I put on my clothes when you take off your clothes. What am I?
No matter how little or how much you use me, you change me every month.