Be careful not to disorient new users, the “fairly cheap” API cost can pile up to $10 million quickly if you’re not aware of how it works. Not to mention the API leaks. Just as a word of caution, you will have to pay for everything, including testing your code and implementing it to the user. If your user find a way to your ‘firebase’ or to your API key and very smart, you’ll be billed on behalf of your users 
