There is a purchase I've made in the past (which I won't name right now because I'm waiting for a reply from the developer) which is now no longer downloadable from my Library. The developer removed all the downloadable content and replaced it with a 0-byte placeholder.
Are Itch.io developers permitted to do this? It seems like if we purchase content here we should have some kind of protection from a developer who decides to permanently delete it, regardless of their reasons for doing so.