Gst registration doubt

BIBIN (3 Points)

20 May 2020  
If i want to open an online store (ie. My own Website and mobile application) with cash on delivery only, do I need to take registration under gst :
1- If all sales are within one state or
2- Inter state sales are involved

Also if I use any payment gateway for sales receipt, is there any change?
Is there any other statutory requirements needs to be complied