PT under GST

No it is not cover under GST .
Professional tax being levied by the State Government, is different in different states. 

Is it necessary to register for PT one who has GST registration. (for proprietor)

Professional Tax and Trade license we
remained after the existence of Gst. since it comes under states domain. VAT also subsumed with GST. Then why not PT? ceiling limit of PT is Rs. 2500.annually. At the time of filing application of GST registration this field ( PT). If you do not have PTEC you have to leave this field blank and proceed further.

IN MY VIEW ITS PART OF SALARY , HENCE DO NOT COVER UNDER GST