Municipal Code Section 21-3 defines the business of rental of commercial real estate as including every person, whether as an owner-lessor or leaseholder-lessor, engaged in the business of leasing, renting, subleasing, subletting, providing, exchanging or trading without loss of ownership or leasehold any real property, dwelling, building, structure, premises or portion thereof for industrial, commercial, office, warehouse or other entrepreneurial uses or purposes other than for the immediate use or purpose of dwelling, sleeping, lodging or general residency.