Answer:
I am not alive but I can die. What am I?
I run up and down the stairs without moving
I am enjoyed by some despised by others. Some take me for granted some treasure me like a gift. I last forever unless you break me first.
What gets bigger when more is taken away?
I don't live within a house nor do I live without. Most will use me when they come in and again when they go out.
When is it bad luck to see a black cat?