It shall be unlawful for any person to operate a warehouse in the state of Washington without first having obtained an annual license from the department, but this chapter shall not apply to warehouses that are federally licensed under the provisions of 7 USC 241 et seq. for the handling and storage of agricultural commodities. A separate license shall be required for each warehouse that a person intends to operate, but any person operating two or more warehouses that constitute a station may license the warehouses under one state license. All the assets of a given station that is licensed under one state license are subject to all the liabilities of that station and for the purposes of this chapter shall be treated as a single warehouse, requiring all the stocks and obligations of the warehouses at a given station to be treated as a unit for all purposes including, but not limited to, issuance of warehouse receipts and receipt and delivery of commodities for handling, conditioning, storage, or shipment.