In WI the equipment to put the refrigerant into the unit once installed has to be registered with the state and you have to have a licence to use it.  

Come to find out he was not licenced.

@Pete AckersYou do not require a real estate licence to buy and sell properties in Canada ... otherwise every homeowner would need to be licensed.  

Perhaps I can licence for free to a community group or a school... 

I am a licenced and bonded contractor and since I limit the number of projects I do outside of my own properties I charge a very reasonable rate.

@Paul StoutI'm thinking about going to get my commercial brokerage licence because it only requires an additional month of schooling.

It doesn't matter if they are licenced or not, it is only to report money paid to someone else for services in the course of business.

I've only done research online in regards LLC licence pros and cons insurance , management rules in California ect. and for some reason everyone (not investors) keep telling us we are thinking too big and we should start with a home.

HERE IS THE INFO ON THE CITY WEBSITE FOR A CONTRACTORS LICENSE REQUIREMENTS.Contractors Get Approval by the City Planning Department A Completed State Contractor License or Affidavit / Workers Comp FormRegister a Trade Name, Fictitious Name, DBA, etc.Cost of Business LicenseBusiness Tangible Property Tax What you need to bring with you if you apply in personWhen applying in person, please allow at least one hour to complete the application process.

Some states require DBA or fictitious business name filings to be made for the protection of consumers conducting business with the entity.A company is said to be "doing business as" when the name under which they operate their business differs from its legal, registered name.