Help me understand PDF Maker pricing
The pricing plans are available here:

You will see PDF Documents Generated under each plan. This is how many times you can generate and download PDF files in a month. One use event occurs each time a PDF document is downloaded. For example, in a scenario where you offer learners to download the typed responses they submitted in the course, and 5 learners take your course one time each: there will be 5 downloaded documents, and you will use 5 credits.

You can track your current usage and your remaining credits on this page:

There is a default email notification that goes out when you exhaust 80% of the credits for the month, so this will give you enough time to make arrangements if needed. You can choose to upgrade to the next plan if you’d like to keep using PDF Maker in your courses or do nothing. If you run out of credits, you will not be able to generate PDFs for the remainder of the billing period, and the credits will reset with the next billing cycle. You can verify that the notification is turned on (or turn it off if needed) on the Account page.