In this post: E-Cycles - Fast Professional Rendering, 100% compatible with Cycles! NEW: 2.93.1 available! - #4001 by bliblubli, @bliblubli said that E-Cycles is GPL. It’s sad that he doesn’t fully respect it. I hope @eklein won’t do the same.
To be honest, I am a bit surprised that @bartv and @moderators allow add-ons developers not to respect software licenses on the forum.