If you don’t have the diagnostic and tuning packs licensed or if you use a standard edition, features like AWR and ASH are not available. These features are essential to analyze the activity of your databases.
ASH (Active Session History) is certainly the most improvement in recent years in terms of monitoring activity.
It has radically changed our approach to performance problems. This feature has now become essential and many articles have been written about its usage.
An alternative solution exists that allows you to have all the necessary elements to make your analysis :