The lead and trial maximizer will show you who is currently on a trial that has already expired. The trial expired tab will show you how long ago that trial expired. To view this, go to:
Left Side Menu Bar > Maximizers > Lead & Trials Maximizer
Under "Trial Maximizer" page, scroll down and select "Trials Expired".
You can see how many classes they have attended on the membership (If they are on a class credit membership), when their membership expired, when their last attendance was (If they are on a class credit membership), the last action taken on the contact from the maximizer, and which trial phase they are under.
You can also perform actions on them by clicking the "Take Action" button at the right side of the page.
Note: You have a stat for expiring memberships on your dashboard. It's important to keep track of the upcoming expirations so you can contact the student ahead of time and get them to renew or upgrade.