Archive databases for previous years can be detached and moved to a backup storage if needed.
When a yearly archive database is created, it will be created beginning on the first day of the selected month. For example, if you select Jan, the database will contain events for 12 months beginning on January 1.
Once the configured Archived job has archived the last event with a time stamp of Dec 31st, then the archive database will be de-activated and a new Archive database will be created for the next calendar year.
At this point the de-activated Archive database may be detached and the .mdf and.log files moved to less expensive storage.