Does anybody know that google assistant SDK is available for commercial use or not?
If available how can I buy its License?
Per the Google Assistant SDK Terms of Service, you may not commercialize your Project without written permission from Google:
Google provides the Assistant API only for developmental use on your Project devices. You may not:
a. commercialize your Project without written permission from Google;
b. incorporate or use the Assistant API with any standalone software applications that are not necessary for operation of your Project device; or
c. circumvent the limits Google places on the number of queries your Project may issue, Users it may support, or any other limit Google may put in place.