You'll probably want a sub-query / sub-report to look at SY_ActivityLog for the last login date / time.

If you aren't already using unified login - I recommend you take a look. Enabling Unified Login will bypass the need for a local password for Sage 100 and instead authenticate users through their Windows login. The big benefit to this is that in a secure environment when you are completing the checklists for password rules - you will answer that Sage follows the same password rules as your network login.

Also, DSD Business Systems offers L031- LM-1031 User Login Activity Log - which they describe as

This Extended Solution to the Library Master module creates a log entry each time a user logs in or out of Sage 100. This Extended Solution does not track ‘Change User’ options and is not company-specific; enable it in one company code and it is on in all of them.