Absolutely.  If you are already a certified massage, yoga or fitness professional you can practice after taking Level I, providing your insurance provider has a cover for Thai Massage.  If you do not have prior training, you may need to increase your knowledge and training level through further levels of Thai Yoga Massage, Yoga Teacher Training, or Massage Training.  Check out the local governing bodies in your area for training requirements.  In Australia, the professional organizations include IICT, ATMS, MAA, AAMT, and Yoga Australia.