On the Creator plan and above, you have the option to activate usage-based billing. This will enable you to pay for additional credits used after exceeding your monthly quota. To enable this feature, please navigate to your Subscription page where you will be see a toggle to enable usage-based billing.
Usage-based billing offers a fixed price for each additional 1,000 credits used over your limit. The cost of these credits depends on your plan. Please see What is the price for usage-based billing? for details.
The additional credits are either billed at the end of your billing cycle, or when the outstanding balance exceeds 2 times your usual subscription price.
If you go over this limit and decide to upgrade or downgrade your subscription, you will be immediately charged for this outstanding usage-based balance, as well as the price of your new chosen subscription plan.