> The creators of those materials never give permission to use.

Not to be glib, but I think that's where things went wrong...?

I'm not a founder, but "relying" on copyrighted materials is bound to fail sooner or later.

So ... design a licensing scheme, and approach the copyright holders. It will likely be difficult, but being educational material, they're likely more open to and used to licensing than general market suppliers.

Ideally, you'd have done this up front, but better late than never.

you can follow what openai does with respect to nytimes complaints recently.

Give creators a cut, it is only fair.

Dupe: https://news.ycombinator.com/item?id=38898450