An apparatus and method are disclosed for temperature measurement that includes performing a first \u0394Vbe measurement of a first temperature of a diode circuit comprising a transistor and, subsequently, performing a first Vbe measurement of a second temperature of the diode circuit. The invention includes generating a number of activation keys, each of which is specific to one of a plurality of in-field devices having inactive options resident in a memory of each of the plurality of in-field devices, and sending each representative activation key and a verification script to each of the in-field devices. A database associates values of the key with categories of service.