In the "Security => Certificates" page as shown below, you can manage the certificates of your publication or ebook.
To add a new certificate, click Add and enter the name of your new certificate. Only alphanumeric characters and spaces are allowed.
To configure the properties of a certificate, either double-click on it or select it and click Configure.
To remove a certificate, select it and click Remove. Note that the Default certificate cannot be removed, and you should always have at least one Registered certificate.
To make a key for a certificate, please select it and click "Make Key". The key generator will be displayed.
To reset the evaluation period on your own computer, click Advanced Options in the ribbon and Reset.
To determine how the unique system ID is generated, you can click Advanced Options and choose one option.
See also Certificate Properties