[Lordzy]

https://sampwiki.blast.hk/wiki/OnPlayerKeyStateChange

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
 if(newkeys & KEY_NO) //Normal no response is of key "N".
 {
   //Stuffs here.
 }
 return 1;
}

I suggest you to read the wiki of OnPlayerKeyState first.