What are Free pages
When you create a new model, it has 'No Active Plan' associated by default and these are Free models. Your account comes with 500 pages and these can be used on the Free models in your account. This helps in cases where you want to test out a new model/use-case without incurring charges for usage.
Please note, Usage on models with a Plan associated is counted separately and is not deducted from the 500 pages.
What are Included pages?
If you activate a Pro plan on your model, the subscription fee of $999 includes 10,000 pages (0.1/page x 10,000 -> $999). This means you get charged for overages (at 0.1/page) after you cross 10,000 pages on the Pro model.
If you activate the Starter plan on your model, there is no subscription fee and you only pay for pages you process. Hence, there are no pages included on the model and you will get charged for usage (at $0.3/page) for any pages processed on the Starter model.