If you use self-signed certificates on cPanel and WHM, they will still expire each year. You may find yourself getting an email such as:
The SSL certificate for ftp on host.example.com will expire in less than 30 days.
Your server’s SSL certificate for ftp will expire in less than 30 days. You need to install a new certificate as soon as possible. You can install a new certificate using WHM’s “Manage Service SSL Certificates” interface: https://host.example.com:2087/scripts2/manageservicecrts (Main >> Service Configuration >> Manage Service SSL Certificates).
To resolve this, click the link as suggested by the email. Then, next to each service, click “Reset Certificate”. This will generate a fresh certificate and automatically install it.