The ZPM reports this state in the following cases:
Keyless trial expires: Activating the ZPM without a key will allow ZPM to run in keyless trial, after the 60 day trial the keyless trial will expire.
Key based trial expires: Once you enter a valid trial key the ZPM will be activated as a key based trial. Once the license of the trial key has expired it will behave as an expired key based trial.
When the ZPM trial state expires after the alloted period it returns to “ZCM Only State”. See Section 9.1, Using the Patches Tab within a Server Group.