The Apify platform has a number of services that are charged based on their actual usage, such as Actors, proxy, data transfer, or storage. See Platform pricing for the full list of platform services. Each subscription plan comes with a certain amount of credits that are used to pay for platform services. If your platform usage in a given billing cycle exceeds this amount of credits, the excess usage will be added to your next invoice, and you will get a notification. If you're on the free plan, your access to Apify platform services will be blocked until the beginning of the next monthly cycle. Note that unused usage credits are not rolled over to the next billing cycle, and they expire at the end of the billing cycle.