Answer:
I’m hard as a rock and as light as a feather. I’m passed on to one another. Poor people need me and rich people have me.
I am two-faced but bear only one. I have no legs but travel widely. Men spill much blood over me. Kings leave their imprint on me. What am I?
I am the tool for inspiring many. Buy me in the store for not much more than a penny. Don't overuse me, or my usefulness will go. What am I?
I can be short and sometimes hot. When displayed I'm never cold. What am I?
I belong to you but others use me more often than you do. What am I?
No matter how little or how much you use me, you change me every month.