I made a simple tileset and i was thinking of selling it, but i have no idea how itch.io handle stuff like permissions, commercial use or not and etc, if anyone can help me with that it would be greatly appreciated.
You can pick one of the popular licenses in your project metadata, or else simply add your own in the description. We don't mandate it, but anecdotally people don't like it when there's no explicit license on assets, and will complain, so it's strongly recommended to add one. Does this answer your question?