If it's even slightly in the money at expiration it will be auto exercised. So unless you want to own the stock you need to close it. Also, if you don't have enough funds in your account to buy the 100 shares of stock at the strike you really do need to close it before expiration.
I'd find another broker if it's really $15 to transact 1 contract.
I'd find another broker if it's really $15 to transact 1 contract.