How to enter a personal Google Books API Key?
By default all queries to Google Books in Gooreader (like Search query, open personal bookshelf, open book, download book) are made via the common Gooreader's API. And as Google limits the number of queries per day, sometimes you can't finish the needed action. To increase the max number of queries per day up to 1,000 you can enter your personal API Key. It's very easy:
1. Register
Google Account if you don't have one.
2. Sign in
Google API Console
3. Click on "Create Project"
4. Activate Books API, accept terms of service
5. Open API Access tab and copy your API key
6. In Gooreader open Options and enter the API Key