Unfortunately, this is not possible since we do not approve SSL certificates on our Free and Enhanced domains.
One option is to make a self signed certificate for your servers. This will prompt visitors with a security warning and they would be able to accept the security exception. The connection is still secure, you just don’t have a third party verifying the chain of trust.
If you would like a domain with a verified SSL certificate you will need to register your own domain name. In order to continue using No-IP for Dynamic DNS your domain will need Plus Managed DNS. You can also purchase a QuickSSL certificate for a domain name you own and can verify.