I will add to that.
If a trial subscription ends, the AP is factory reset so it can be added to another cloud account or re-imaged to connect to a SZ or an unleashed image.
When paid sucscription expires, the AP will not be manageable from cloud, but AP will not be factory reset. It will have last known configuration to continue to service private ssid clients (psk, radius etc). Only guest wifi will not work (as that is serviced from cloud). The AP will forever be in that state until one of following happens:
1. You renew cloud subscription
2. You factory reset the AP yourself and reimage it to be either unleashed or SZ managed.
Hope this clarifies. We r also working to have a special "migrate" button on the UI to make any transition from one Mgmt to another easier. That is in the roadmap.