Your organization must have a SportsEngine HQ Premium subscription to utilize any Membership and Eligibility functionality.
When viewing a membership, you can easily view the members that are active vs. inactive by:
Log in to "SportsEngine HQ".
From the left navigation menu, click Members > Memberships.
To the right of the membership, click View Active Eligibility.
The Active tab shows you a list of the members with a membership, while the Inactive tab shows those canceled.