Legal Question in Business Law in California

In most cases, belonging to a business or trade association is voluntary, and indeed often is beneficial. In my 50-year career in business and law, I have come across a few situations in which membership in a trade association was mandatory.....or at least one had to pay dues or be subject to the association's rules. Some of these had to do with production of agricultural commodities; others had to do with regulated businesses such as operating taxis. I'd have to know the location and nature of your business to advise you further. Or, you could contact the secretary of the organization and ask what law makes it necessary for you to be a member (if any) of this organization. Possibly you have to belong and pay dues, but more likely not.