Is the user base churning or are you getting multi day active users? Which one will point you in a different direction.
Once the page has been generated where can I host it? The answer will influence your target audience.
And then on pricing what does a credit get me in terms of something tangible - a page, 5 pages?
And for the target audience do they know which model is better? And if so why is it better to use your site than just direct prompt?