Elmo, a door-to-door salesman, entered into a contract to sell the Wilson family $320 worth of household products on credit. The Wilsons later learned that Elmo had failed to purchase a city license to make door-to-door sales and refused to pay him. May Elmo collect from the Wilsons? Why?

Elmo, a door-to-door salesman, entered into a contract to sell the Wilson family $320 worth of household products on credit. The Wilsons later learned that Elmo had failed to purchase a city license to make door-to-door sales and refused to pay him. May Elmo collect from the Wilsons? Why