The refundable component should be shown as liability on the balance sheet. While the charge to the owner and the cost of producing a new FOB would be shown as income and expense.
If, for example. it costs the OC $20 to produce to FOB and there was refundable deposit required of $200, then the OC most likely with charge the owner $220. Which may appear as
$20 (Credit) “Other or Key Income” on Income and Expenditure Statement
$20 (Debit) “keys / fobs expense” on Income and Expenditure Statement
$200 (Credit) “Security Deposits” in Liabilities on the Balance Sheet
As Whale says, the account names are dependant on your particular setup and may not need to be broken down too far. But I would say (IMO) it is essential that the refundable component is held in a Balance Sheet liability account.