The archive function uses the daily backups the Lan-Inspector server creates. Depending how many days you want to let him reach into the past, you can access the complete state of data of each stored day. There is an own service “LaniBackupService” on the server that creates the archives, see 7.2.7 Backups and Archives.
If you select a day from the list, you receive read-only access to all functions and queries ready for the archived state of data.