If the brokerage doesn't require NAR membership, all the better. 

@Thomas Enright If you're a NAR member, RPR will make pretty CMAs. 

From a NAR perspective (Just my interpretation of course) is about giving false statement about another agent.

As for joining the NAR yes if the Brokerage is an NAR member you will need to be one as well.

Here is a link to some frequently asked questions about being an Independent Contractor prepared by National Association Of REALTORS (NAR). https://www.nar.realtor/law-and-ethics/independent-contractor-status-frequently-asked-questions

In past legal actions against NAR, against the MLS, and against large real estate companies, the lawyers bringing the case tended to be small plaintiff’s lawyers seeking a relatively quick payday.

NAR also has educational opportunities for it's members.3. 

@Mark Rogers I’m not a lawyer but common sense tells me this suit is likely to be dismissed because the premise that NAR/MLS can “force” sellers to pay a commission is false.

Do you have to maintain your membership with NAR and your local state association?

You will have annual fees- NAR, MLS, etc regardless if you sell a property in those 2-3 months or not.