seems to have been released on steam.
when can i get my steam key ?
itch.io version is 3.2, while steam version is 3.4.1.
seems steam version is slightly ahead.
im not the dev nor author. but i can say you should receive steam key as well after your purchase. (not demo)
as to promotion from beta to latest version, i don't know. since i stopped using steam for now.
maybe you'd better ask directly to the dev. they should be quite responsive AFAIK.