Don’t worry; any unused credits will be made available to use again in future campaigns! The majority will be transferred from “reserved” to “available” immediately. However, five credits will be withheld under the “reserved” category for a period of three days. As Facebook takes three days to report the funds used in an ad campaign, these five credits will be used as a buffer while Facebook finalizes their reporting. Once the three days are over, what remains of those five credits will be transferred back to your “available” credits.