For my own experience i can mention the webrtc project which is incomplete at all. If i have a decision from the beginning to buy a source code for sure thats because i didnt want to write or wrap it myself. Why bother buying if received nothing?
As a human being i tried to be at the side of excuses that something bad may accure to the developer but not anymore since he is fine and answering other members and neglect or ignore a many of those who put the trust in him. And obviously others have many similar issues in that neglecting with ready excuses which make the whole thing has become too fishy. If for real he is answering and ask for payments on his telegram while many asks about his sudden disappearance then this does not sounds right. Lastly since my old thoughts based on many posts that says he always in a dangerous situation and so on. If @Leandro Vaufran Esteves, says the truth then the developer falls in a big mistake by giving promises that he cant deliver.
I don't know that project, I didn't take it.