I had the same problem and this is the response that I got from Orbbec:
"Thank you for reaching out to us.
The body tracking feature for beta test was free to test earlier up to June 30, 2018. However now it has extended till sept 30, 2018.
Thus, to continue working with the body tracking feature you have to update the license by downloading the Astra SDK again.
Please feel free to download the Astra SDK from here - https://orbbec3d.com/develop/
Please let me know if you have any further questions."
I have a Persee and by changing the date of the device it worked once again without updating the SDK. I believe it should work again for you if you change your computer's date to one previous to July 1st 2018. Although updating the SDK would be favorable