How can you find out if someone has a license to sell mobile homes?

Contact the licensing board in your state. Laws, rules and regulations will be different from state to state. My guess is that the sale of a mobile home will come under very different rules than the sale of a constructed home on a lot. Also, if a person owns a mobile home or a constructed house, he or she can sell it without a license. There is no requirement that the sale of a home must be handled by an agent. In some places, probably everywhere in the US,what is regulated is selling a home that belongs to someone else for a fee or commission.