An EIP is a public IP address used in an ECM instance. If it is idle, IP resource fees will be charged.
An EIP that is not bound to an edge resource and thus idle will incur IP resource fees. If it is bound to an edge resource and takes effect, it will incur public network fees but not IP resource fees. For more information, see Billing Overview.
IP resource fees are postpaid hourly, that is, the fees for an hour will be billed and charged in the next hour.
IP resource fees = EIP hourly unit price * billing period
To avoid incurring unnecessary IP resource fees, bind your EIP to an edge resource immediately after applying for it and release it immediately after unbinding it from the resource.