Can a user view previous video data of a device after I canceled the cloud storage service for the device and the user purchased the cloud storage service for the device again?

No, the user cannot see the information without knowing your user account information. The cloud storage service validity period and data are bound to the device and user information. To use the cloud storage service for a device, a user needs to purchase the service for the device and cannot check video data uploaded under any other user's account.