The FBA Pack doesn't currently show the last time a user logged in (but feel free to add this feature request to the issue tracker).
Currently though you can query the membership database to find out this information. There's a column in the aspnet_membership table named LastLoginDate that should give you the information you need.
The following query should give the last login date for a specific user:
FROM aspnet_membership JOIN aspnet_users ON aspnet_membership.userid = aspnet_users.userid
WHERE aspnet_users.username = 'theusername'
Or just leave the WHERE clause off to get it for all users.
Hopefully the query works, but I don't currently have access to an environment to test it.