As you have probably found, the web user login history can be found by clicking Logs > Audit Logs > HTTPS (or other service). You can then enter a user name to easily find the user's history.
The amount of history you have depends on the log settings. Click Logs > Log Settings > Services to view or change these settings for "Days To Keep Audit Log Records".
If you have the "Archive" box checked, and you want to view records older than what you have retained in the database, follow the path specified in this section and you will find the archived records in CSV files, which can be easily viewed and sorted in Excel. I recommend making a copy before.
You can also export the Audit Log Screen and open in Excel.
If you connect to the GAMFT Database and query the Web User table for last login-date, you could retrieve a list (rowset) of Web Users that haven't logged in since "X" date.
Will that help?
Lead Solutions Consultant