It will be provided by email for itch users, and by license code for gumroad users. It already supports windows, macos, and linux. I don't have a solid estimate for time of release, I'm hoping for the first half of next year. There is a testing group, but for now it is invite only.
Also the name "Pixelit" is the final name for the application. There are a few products with this name, but none of them have a trademark, and they are extremely small/largely unrelated. Trying to name anything without clashes is basically impossible :)