No sale referred to in Section 731.01 shall be licensed or permitted for a period of more than thirty days, Sundays and legal holidays excepted. Such thirty days shall be consecutive except as to Sundays and legal holidays, provided that if the permittee does not sell the quantity of merchandise listed in the application for a permit, he or she may make application for extension of such permit to the Mayor and if upon investigation, the Mayor is satisfied as to the truth of the statements contained in the application for renewal, he or she shall issue a renewal permit for a period not exceeding thirty days. A maximum of two such renewals may be granted, except that if cause is shown to the satisfaction of the Mayor, additional thirty-day renewals may be granted until all the disposable inventory listed in the original application for a permit is sold. No permit shall be issued to any person to conduct a sale at the same location where such applicant has terminated a prior sale licensed hereunder within a period of eighteen months subsequent to the termination of such prior sale; nor shall a permit be issued to a purchaser of stock at a sale licensed hereunder for a period of eighteen months subsequent to such purchase if such purchaser continues to conduct business under the same firm name as that used by the seller of such stock without having adopted a reasonable means of advertising the change in ownership to the public or where, in fact, bona fide change in ownership has taken place and such purchase was a sham transaction intended to deceive the public; nor shall a permit be issued to any person who has not been for a period of sixty days next preceding such sale continuously engaged in the City in the business of selling goods, wares or merchandise at retail. No person who has been convicted of violating any of the provisions pertaining to a sale licensed hereunder shall be issued a permit to conduct such a sale or be employed in any manner in the conduct of such a sale for a period of two years subsequent to such conviction.