Tier re-enrollments can be done only by users with Change loyalty opt-in preference permission for their role.
To allows users to re-enroll guest's whose tier enrollment was previously canceled, log in as an owner and do the following:
At the organization level, click the Admin icon.
Navigate to Organization >Security Roles > User role.
Note: If you do not see Security Roles while logged in as an owner, contact Zenoti Support.Click Permissions tab.
Expand Guest Manager.
In the Guests section, select Change loyalty opt-in preference checkbox.

The users with the configured role can now select the Opt in to loyalty program checkbox in a Guest's Profile and enroll guests whose enrollment was previously canceled.