Patent attributes
A system transfers applications and datasets (files) from a server to a client device and assigns to each file a lease key that will expire at a specified time. A file cannot be accessed unless its lease key is validated. Upon expiration of a lease key, the client device will connect to the server to determine if the lease key may be renewed. If the lease key may be renewed, a new lease key is created and access to the associated application or dataset is restored. If the lease key may not be renewed, the file may be deleted or rendered inaccessible. If rendered inaccessible, the file may be restored in the future without having to re-transmit it from the server to the client device. The server may also revoke a lease key before it expires.