Discourse pricing | Discourse - Civilized Discussion :
What happens if I go over the plan limits?
Your site will never stop working! We understand your site can get a lot of visitors quickly for any number of reasons, and success is something to celebrate! If your site exceeds plan limits for several months in a row, we will contact you to discuss flexible upgrade options.
You can also find an add-on for the standard plan on that site. It adds 100k extra page views among other things.