TI CC2650STK - How to activate ZigBee?
The CC2650ST supports ZigBee, BLE or 6LowPan. It comes programmed with BLE by default, you need to download the BLE sensor tag app from app store and update the FW to the ZigBee image. This will update to a ZigBee image using BLE. The App has the CC2650 ZigBee image included in it, so you just need the latest app. The ZigBee FW image makes the sensorTag into a ZigBee Temp Sensor, Light Sensor and Switch. 

Alternatively you can buy a debug-devpack (http://www.ti.com/tool/CC-DEVPACK-DEBUG) and update to a ZigBee image using SmartRF flash programmer. The FW will need to be built from the ZStack-HomeSDK from www.ti.com/tool/z-stack.

Regards,
TC.