I've had the same issue.
This was the second Itch game I bought, and the other allows me to download the most recent versions as they come out, it's just this one that doesn't.
Its even worse here, I stay in South Africa, for example, $20 is 375 ZAR at the moment, which is close to what I would pay for some A-list games here, depending on the game.
I was a bit disappointed when I saw that I don't get the most recent versions after forking out so much cash for a game that is still in development because I wanted to support the creator.
Viewing post in Knightly Passions 0.55! RELEASE! comments
It's also usually why I don't like buying games in early development. I'm ok with paying a one off payment if the product shows potential or peaks my interest, but for ME to pay YOU (i.e, the developer) to MAKE the game, and to PAY continuously????? Well, welcome to free market capitalism, baby! lol