You should have a running instance in your aws account to allocate it an Elastic IP which does not allow your IP to get disconnected from your project.
You can attach EBS (Elastic Block Store) volumes to one of your instances that is in the same Availability Zone as the volume.
Assuming that you have Launched an Instance, and Downloaded the Key Pair file i.e. your .pem file before connecting to it.
Amazon Elastic Compute Cloud (EC2) is the Amazon Web Service used for creating and run virtual machines (instances) in the cloud.