A medical device configured to receive a physiological signal from a physiological sensor coupled with a patient and to perform a vital signs measurement based on the physiological signal, the medical device comprising a driver circuit that drives one or more emitters of a physiological sensor at multiple wavelengths of light to cause the one or more emitters to transmit the multiple wavelengths of light through body tissue of a patient, a hardware processor in communication with the physiological sensor. The hardware processor is configured to determine a number of remaining credits, in response to a determination that the number of remaining credits satisfies a threshold, enable continuous monitoring of the patient based on a physiological signal for a limited period of time, update the number of remaining credits, measure, from the physiological signal, a plurality of values of a physiological parameter, output, for the limited period of time, the plurality of values of the physiological parameter audibly or to a display.