The availability of the Dictionary service depends on the license you have.
To recover from a data loss scenario or any other causes of data corruption or deletion, you are advised to perform back-ups of Talend Dictionary Service on regular basis and store the database and files in a secure place.
Talend Dictionary Service stores all the predefined semantic types used in Talend Data Preparation. It also stores all the custom types created by users and all the modifications done on existing ones.
To back up a Talend Dictionary Service instance, you need to back up the MongoDB database and the changes made to the predefined semantic types.