We need a report of all the users who hits our App, number of times that the each user logs into our application.
Could you please let us know, what could be the best way to achieve this.
The most flexible approach, the one that would give you more control although at the cost of some complexity would be for you to configure the export of your tenant audit logs to a system that is unaffected by retention times and then query that information from the logs. Each authentication would generate a log that would include the client identifier along with the timestamp which would give you the fine-grained information you require.
There a bunch of extension that automate the export of logs to external systems so you may want to review this list to see if any would be of use.