Said Board shall have full power to suspend for not more than ninety (90) days or revoke for proper cause any license or renewal of same after a full hearing of all parties in interest. P.L.L., 1915, §663-1 1927, §663-1 1930, §663-1 1938, §787 1949, §487 1969, §3-10 1906, ch. 244, sec. 9 1957, ch. 450, §487