My Gemini key cannot make cover pictures. It says the key has no picture quota left. Why?

Google's free tier for Gemini API keys may not include pictures, even when the same key writes books without any problem. From version 1.9.22, BookyAI says this plainly instead of showing Google's raw error. You have three options: turn on billing for the key in Google AI Studio, add an OpenAI API key in Settings (under Extra tools, Covers), or upload your own cover picture. If the message says Google's image service is busy, simply try again in a minute.