There is no penalty for letting your Option expire. If it is OTM, it will expire worthless and if you are a option buyer, you will lose the premium paid. If you are a option seller, you will get to keep the premium recieved.
Also, if Option expires OTM there is no brokerage applicable as it will expire worthless.
As explained above, brokerage will not be applicable if your Option position is OTM as it will expire worthless. But if you are squaring-off before expiry then brokerage will be applicable as usual.