I, personally would not take the advice of anyone on this forum regarding the legality, and this really applies to all legal questions presented here. The only way to find out the legality definitively, is to contact the FAA Office of the Chief Counsel and ask for an interpretation, or have your case tried in court. That said, there are a lot of areas in the FAA regulations that are not clearly defined, and when you step into that area you really don't know. Now if you were operating your drone actively for commercial purposes without your 107, and the FAA had a complaint, it's quite possible they may look into that. On the other hand, if someone is selling old amateur (uncontracted) photos that were taken legally, that would be a subsequent action that has nothing to do with with the original and legal operation of your drone. I personally don't think they would do anything, but if you need to know 100%, get an interpretation.