Each member of the boards mentioned in section 45:1-2 of this title shall be entitled to his actual traveling and other expenses incurred in the performance of his duties, which sum shall be paid from the license fees and other sources of income of such boards. Such boards shall also be entitled to expend from their income such sums as shall be necessary to defray all proper expenses incurred by them in the performance of their duties, including the compensation of any of their officers or agents whom they are authorized to compensate. Such boards, if authorized to collect an annual registration or license fee from persons licensed by them, may retain in their treasuries the fees so collected and use the same for the purpose of defraying the expenses of securing evidence against and prosecuting persons violating the provisions of the laws with the enforcement of which they are charged, or, in case the revenue of the boards from other sources shall be insufficient to pay the salary of their secretaries and their other expenses, such fees may be expended for such purposes. Such boards shall be entitled to retain, in addition to the above, at least one hundred dollars in their treasuries for the purpose of preparing and holding their examinations. On or before October thirty-first in each year such boards shall pay to the state treasurer all moneys remaining in their treasuries, except as above stated, which sum, when so paid, shall form a part of the state fund. Such boards shall keep accurate accounts of their receipts and expenditures, which accounts shall be subject to audit by the state comptroller.