Mine didn't have instructions either, so I emailed them. They sent me these:
USAGE
• Charge battery before use.
• Turn 510-threaded cartridge clockwise onto 510-threaded vape pen battery. DO NOT overtighten.
• Push button rapidly 5X to turn ON/OFF. (Note: LED light will flash when battery is turned ON/OFF).
• Push button rapidly 3X to alternate between 3 heat settings.
• Pre-heating: Push button rapidly 2X (Note: LED light will change colours).
• Push button 1X to quit pre-heating.
• When ready to use, press and hold the button and inhale through the mouthpiece.
• Turn off and remove cartridge from vape pen battery when not in use.