Section 63. Each member of the board shall receive twenty-five dollars for each day or portion thereof spent in the performance of his official duties; provided, that the total sum paid to any member thereof shall not exceed six hundred dollars in any one year; and, in addition, all necessary traveling and incidental expenses actually incurred by him in connection with said duties. Such compensation and expenses shall not be in excess of the annual receipts for examination and licensing paid to the commonwealth by the board.