If a master plumber or gas fitter goes out of business, takes other associates into the business with him or if an organization with which he is associated changes, he shall promptly notify the director, in writing, of that fact, and his registration card shall become void. Before entering into a new business organization, he will be required to re-register and take out a registration card in the same manner and at the same cost as at the time of the original registration. (Mont. Co. Code 1965, § 95-28.)