The registered email is the username that you use to login to your AEserver account (client area). This is the email where AEserver sends out notications, announcements and billing details regarding your services.
It is generally recommended to use a separate email ID for that login. The reason being that if your hosting or domain gets expired, you will not receive any udpates from AEserver on that particular email.
To change the registered email ID or any other details, please follow the steps provided below:
1. Login to your client area (https://www.aeserver.com/my/clientarea.php)
2. Click update
3. You can now make the desired changes as required.