Answer
The name of the "Update" key was changed recently in order to better reflect the type of service that was being purchased.
With a maintenance key, the system is able to be upgraded, or maintained with the most current version of the software, for the life of the key.
This maintenance key is distinct from a support key which allows you to access via email or phone a member of support staff during the designated hours for the life of the support key.
Keywords:upgrade update support maintenance key