To know the last accessed date of Database run the following query
SELECT DatabaseName, MAX(LastAccessDate) LastAccessDate
FROM
(SELECT
DB_NAME(database_id) DatabaseName
, last_user_seek
, last_user_scan
, last_user_lookup
, last_user_update
FROM sys.dm_db_index_usage_stats) AS PivotTable
UNPIVOT
(LastAccessDate FOR last_user_access IN
(last_user_seek
, last_user_scan
, last_user_lookup
, last_user_update)
) AS UnpivotTable
GROUP BY DatabaseName
HAVING DatabaseName NOT IN ('master', 'tempdb', 'model', 'msdb')
ORDER BY 2
