Sourren
lol - sorry if this is a stupid question.
But what exactly is a 'registered' comic book artist?
Are you with a publisher or company?
No problem. That's not a stupid question at all. "Professional" refers to any kind of recognition by a qualified group.
Typically, one who works with a publisher or company is considered a professional. However, there are other methods as well, such as becoming a well known self published writer/artist, or being recognized by a qualified group.
I am granted the title of "Creative Professional" through Comic Con International. There is an application process in which they review your work and consider it professional grade level work or not.