If you dream about any kind of the money, then it signifies the valuation for the things you get from people around you such as the favor, lending money, giving help when it is needed. If you pay the bill, it shows that you feel that you owe something to someone because of the favor they did to you. You think you have to pay for what you got or the subconscious mind of yours is thinking that way. If you won the lottery or the other person gave you a great amount of the cash, you are feeling very lucky in some situation, however you know that you will have to pay for that in other way as well. If you dream that the other person must give you the money, because you borrowed it to him/her before, it means that you feel unappreciated and people should give back when they receive the goodness from you.
Read more about dreaming of Bills (cash, as in one dollar bill) in other dream meanings interpretations.