I am wondering about the possibility of publishing a paper which was presented in a conference. If there is no proceedings. Do we have right to do that?
A conference paper has a somewhat different format than a journal paper, you could adjust your paper to the format required by the journal where you chose to publish your paper, and then send it to the journal with a mention that the paper is based on the relevant conference.
publishing an abstract in a journal or presenting it at a meeting does not prevent an author from submitting a full paper on the same abstract to a journal for publication. This is, in fact, quite common, and should be noted on the title page of the journal submission. Many biomedical journals follow the recommendations of the ICMJE, the International Committee of Medical Journal Editors, whose policy specifically says that publication of an abstract, “does not prevent a journal from considering a complete report that follows publication of a preliminary report, such as a letter to the editor, a preprint or an abstract or poster displayed at a scientific meeting.”