Question: the iron bank will have its due?
Answer: debts. She walks away confident, but she shouldn't be: In season four, Olenna Tyrell reminds Tywin Lannister that just like a Lannister always pays his debts, "the Iron Bank will have its due." And in season five, Cersei sends Mace Tyrell to Braavos on behalf of King Tommen to bribe the Iron Bank.