title: Relation between EIP and ENI in AWS/EC2
body: <p>I'm a new user of AWS/EC2. I'm not sure that how Amazon manage a pair of EIP and ENI.</p>
  
  <p>What I want to do in ec2 is to use a software license which is related to MAC address. So for using this license, I have to keep a same MAC address on EC2.</p>
  
  <p>Actually I've already prepared my EIP, and it looks this EIP is related to specific ENI. So I think that the pair of this EIP and ENI is keeped unless I release this EIP or ENI. Is my understanding right? </p>