A multi-frequency ultrasound therapy apparatus is configured to operate at its center frequency and at the higher harmonic of its center frequency. The center frequency can be for the entire apparatus or for each ultrasound source element. At least one source element can generate ultrasound energy at its center frequency while, simultaneously, at least another source element can generate ultrasound energy at the higher harmonic of its center frequency. In addition, the same source element can generate ultrasound energy at its center frequency and the higher harmonic of its center frequency, respectively, but at different times. A data storage unit that stores encrypted and encoded data is disposed on the apparatus. The encoded data includes a unique identification code of the apparatus, the condition of use of the apparatus, the center frequency of each source element, the ultrasound efficiency of each source element, and/or other parameters relating to the apparatus.