1) Read the frequency label on the MOTE.
2) If the frequency label is missing, you can tell what type of device you have by looking at capacitor C13 (MICA2) or C12 (MICA2DOT).
if C13/C12 IS NOT populated (capacitor missing), then the device is built to operate in the 868/915 MHz range.
if C13/C12 IS populated (capacitor present), then the device is built to operate in the 433 MHz range
As yet, there is no processor accessible setting (in EEPROM, FLASH or other) that indicates the device's operating frequency band.