The Health Key and Certificate Management service is necessary to manage X.509 certificates. These may be necessary for security related protocols such as SSL/TLS, IPSec, S/MIME, Smartcard, SSH, HTTPS, LDAPv3, and EAP. Many of these protocols are commonly used in corporate settings, but are also often necessary for home users as well. Since this service is set to manual by default, it is only called upon when needed, so you are unlikely to save any resources by disabling it. If you disable this service, features and applications that rely on any of the above protocols may not function properly.