Patent ID: 7987365

Claim:
A subscription-based computing device having hardware and a subscription enforcer implemented in the hardware such that the level of use of at least a portion of the computing device is premised upon whether a corresponding subscription to so use is current, the subscription enforcer comprising: a secure accumulator accumulating a usage value as the computing device is being used, the secure accumulator being persistent and non-volatile and preserving the accumulated usage value therein even when power is not applied to the hardware; a persistent re-settable expiration value register for storing an expiration value, the expiration value register being accessible and re-settable only by the subscription enforcer, the subscription enforcer allowing the computing device to operate in a subscription mode without hindrance and with full use when the usage value in the accumulator is less than the stored expiration value in the expiration value register, and allowing the computing device to operate in an expiration mode comprising hindering the use of the computing device hardware to a minimal functional level of use comprising use sufficient to at least communicate with the subscription service and to re-set the expiration value register to a new expiration value when the usage value in the accumulator reaches the stored expiration value in the expiration value register to signal that the subscription for the computing device has expired; a subscription extension token that is obtainable for the subscription enforcer prior to or after the subscription has expired, the token including therein an extended expiration value, a key ID, and a validation signature based on the extended expiration value and the key ID, the validation signature for being validated according to a validation key corresponding to the key ID; a key register having stored therein a validation key accessible only by the subscription enforcer; a key ID register having stored therein a key ID corresponding to and identifying the validation key stored in the key register; and a validator for validating the validation signature of an obtained subscription extension token, whereby upon receiving an obtained token, the subscription enforcer resets the expiration value in the expiration value register to the extended expiration value of the obtained token and removes the hindrance to the computing device hardware if the key ID in the obtained token matches the key ID in the key ID register and if the validator validates the validation signature of the obtained token based on the key in the key register.