Why is the woman so happy? What advice does the man give the woman?

W: I am happy I started carrying the credit card that the bank gave us.
M: Why is that, Kate? Did you use it to buy something?
W: I surely did. On my way home I stopped at the store to buy some beef for dinner because I didn’t have any cash with me.
M: And they permitted you to pay with the card?
W: Yes. They didn’t even ask me to give the ID.
M: You have to be careful. If you lose them and someone finds them, the bank will charge you for what you buy.
W: How much has the bank allowed us to spend with the card?
M: Fifteen hundred dollars. The bank encourages us to use the card, but they will also require us to pay them back.
W: You are right, Henry. I’ll remember that. But the card surely makes it easy to spend money.