You can generate a specific API key, and make sure to monitor it by setting a budget limit to it. They should explain this to people in their form to avoid people pasting their main key.

For those who do not want to paste OpenAIkeys to other peoples web pages, there are local solutions.

For example, these audiobook generators runs fully offline. https://github.com/Finrandojin/alexandria-audiobook https://github.com/senigami/audiobook-studio.pinokio https://github.com/topics/audiobook-generator