Free NX X server error

When I try to run NX this is what I got →

emil:/home/emil # /usr/NX/bin/nxclient
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified

nxclient: cannot connect to X server :0.0

They only way to make it working I found is this:

xhost +local:emil

But I have to type this every reboot :
Someone find better way?