The books of account shall be kept up-to-date. The columnar books, deposit books, savings account passbooks, cancelled checks, checkbooks, deposit slips, bank statements and copies of financial statements of games of chance operations (form GC-7), financial statements of raffle operations (form GC-7R) and financial statement of bell jar operations (form GC-7Q) for the previous 18 months, and all other books of account, shall be available at all games of chance license periods and other reasonable times for examination by the commission, clerk or department and officer or their representatives. The books of account and all documents supporting the entries made in the books of account shall be kept by the licensee for a period of not less than four years.