If you want to see last seen dates for users you must follow the instructions below.
You should export your user data from Jira User Management section.
Click the Export User button.
Check product access button and click the download button.
Import the downloaded file through the advanced user manager.
Click the Show Last Seen button.
Click the Next button in the opened window
Browse Downloaded file and select for import
7. Now you can see the last login date of the users and avoid paying too much license cost.