Generally, a professional is one who makes a living doing the task or art involved. Here are definitions:

–adjective
1.
following an occupation as a means of livelihood or for gain: a professional builder.
2.
of, pertaining to, or connected with a profession: professional studies.
3.
appropriate to a profession: professional objectivity.
4.
engaged in one of the learned professions: A lawyer is a professional person.
5.
following as a business an occupation ordinarily engaged in as a pastime: a professional golfer.
6.
making a business or constant practice of something not properly to be regarded as a business: “A salesman,” he said, “is a professional optimist.”
7.
undertaken or engaged in as a means of livelihood or for gain: professional baseball.
8.
of or for a professional person or his or her place of business or work: a professional apartment; professional equipment.
9.
done by a professional; expert: professional car repairs.
–noun
10.
a person who belongs to one of the professions, especially one of the learned professions.
11.
a person who earns a living in a sport or other occupation frequently engaged in by amateurs: a golf professional.
12.
an expert player, as of golf or tennis, serving as a teacher, consultant, performer, or contestant; pro.
13.
a person who is expert at his or her work: You can tell by her comments that this editor is a real professional

As you can see, it can be taken in at least two ways.
I am a professional, because I'm good enough, maybe barely, to have made a living playing music for close to 40 years.
I can read music, but I don't anymore. Doesn't make me any less a pro.
I can, or could, play trumpet at a high level. Never made a dime doing it, so NOT a pro.
That's my take.
DonM