When someone refers to be someone doing something on a professional basis, the assumption would be they get paid for it. To refer to someone as a professional traditionally would have meant a doctor or a lawyer would expect some advanced education, membership of a group. Now a professional seems to be water down to mean anyone that works in an office.
I always think if someone describes them self as a professional it probably means they are not in the traditional sense if they were a professional in the traditional sense they would most likely say what they do not use some vague diluted term.
Bank worker, public servants, HR all these people may describe as professional yet not have any advanced or speclized education and not necessarily belong to a professional body.
It would depend if using as adjective or noun, see Synonyms it would depend on the context and how is being used.
It can just mean in some contexts someone that is being paid to do something rather than someone who is not being paid.
http://www.oxforddictionaries.com/definition/english/professional