If you are serious about your profession and you want to be recognised as a professional, it is in your best interest to do so.
Further to this:
In terms of the SAQA Professional Body requirements: A professional designation indicates registration of the individual with a professional body, and where relevant, the right to practice in the particular field of expertise governed by the professional body.
For all plumbing works completed, plumbers are required to issue a PIRB plumbing certificate of compliance. Only PIRB Licensed Plumbers can issue these certificates.