Every licensee shall at all times have on demand deposit in a federally insured depository institution or in the form of cash on hand or in the hands of his agents or in readily marketable securities an amount equal to all outstanding unpaid checks sold by him or his agents in Missouri, in addition to the amount of his bond. Upon demand by the director, licensees must immediately provide proof of such funds or securities. The director may make such demand as often as reasonably necessary and shall make such demand to each licensee, without prior notice, at least twice each license year.