Given your model, consider publishing a time-to-live metric: if you get no further donations, this is how long the service will last.

Then people who care about 1 month, 1 year, or 10 years can decide accordingly.

And also describe the processes for extracting data, etc.

Finally, talk about your motivations. You raise the issue by pricing at $0 without addressing the concerns that raises, in a era when "free" means the user is the product and when LLM's are a giant content vacuum that copies without attribution.