The author (Rob) writes:
All textures here are CC0 (public domain). No paywalls, accounts or email spam. Just download what you want, and use it however.
Since all of the income for this site comes from the community, it's only fair that the community gets to decide what happens with it.
All Patrons have access to a private Trello board where they can add ideas and vote on new types of textures, and generally decide where the money goes.
If you want to get involved and help keep the site alive at the same time, consider supporting Texture Haven on Patreon.