No limited liability company organized under this chapter may render professional service within this state except through its members, employees of its members, managers, employees, and agents who are duly licensed or otherwise legally authorized to render those professional services. However, this provision shall not be interpreted to preclude clerks, secretaries, bookkeepers, technicians, and other assistants who are not usually and ordinarily considered by custom and practice to be rendering professional service to the public for which a license or other legal authorization is required from acting as employees, managers, or agents of a professional limited liability company.