When logging into Endpoint Protection Cloud (SEPC), an administrator or account administrator sees that devices are classified as "unassigned".
The user subscription model assumes each end user will have their own SEP Cloud user account that they will login to and enroll their own devices in protection. If devices are not enrolled by an end user, or transferred to another user after enrollment, those devices will appear as unassigned.
Unassigned devices are still protected and monitored. The main reason to assign a device to a user is to ensure license usage reporting is accurate for customers using the user subscription model and to ensure alert notifications have an associated user.