Address recommendations are straightforward: we recommend keeping any address that doesn’t cost you money, and we recommend deleting any that is unused and costing money. Addresses may be inexpensive individually, but they can account for a significant cost if left unattended.
In AWS, addresses cost you money if any of the following conditions apply:
We go through all of your elastic IP addresses and look for any that are unattached, attached to an unattached network interface, or attached to an instance that is not running.