Development Assistance GUI Permissions

Sorry that i ask alot but i have a plugin that gives users drinks but i want to make it donator only so where to i put player.hasPermission("Drinks.DrinkName"); ? I want it so each Drink has its own permission and if you dont have it the plugin returns a message and it wont let the person have the Drink and will exit the GUI.

Code:

package me.jake2967.Drinks;

import java.util.HashMap;

import net.milkbowl.vault.chat.Chat;
import net.milkbowl.vault.economy.Economy;
import net.milkbowl.vault.permission.Permission;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Entity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.event.player.PlayerRespawnEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.plugin.RegisteredServiceProvider;
import org.bukkit.plugin.java.JavaPlugin;

public class DrinksGUI extends JavaPlugin implements Listener {
   
     public static Permission permission = null;
        public static Economy economy = null;
        public static Chat chat = null;

        public static Inventory GUI = Bukkit.createInventory(null, 9, ChatColor.DARK_RED + "" + ChatColor.ITALIC + "" + ChatColor.UNDERLINE + "Drinks");
    @SuppressWarnings({})
    public HashMap<Player, Entity> Menu = new HashMap<Player, Entity>();

    public static void setItems() {
        ItemStack Coke = new ItemStack(Material.POTION, 1, (byte) 2);
        ItemMeta Cokemeta = Coke.getItemMeta();
        Cokemeta.setDisplayName(ChatColor.RED + "Cola");
        Coke.setItemMeta(Cokemeta);
        GUI.setItem(3, Coke);

        ItemStack Lemonade = new ItemStack(Material.POTION, 1, (byte) 5);
        ItemMeta Lemonademeta = Lemonade.getItemMeta();
        Lemonademeta.setDisplayName(ChatColor.YELLOW + "Lemonade");
        Lemonade.setItemMeta(Lemonademeta);
        GUI.setItem(4, Lemonade);

        ItemStack Vodka = new ItemStack(Material.POTION, 1, (byte) 9);
        ItemMeta Vodkameta = Vodka.getItemMeta();
        Vodkameta.setDisplayName(ChatColor.AQUA + "Vodka");
        Vodka.setItemMeta(Vodkameta);
        GUI.setItem(5, Vodka);
       
        ItemStack Creator = new ItemStack(Material.ICE, 1);
        ItemMeta Creatormeta = Creator.getItemMeta();
        Creatormeta.setDisplayName(ChatColor.AQUA + "Created by KrypticIce.");
        Creator.setItemMeta(Creatormeta);
        GUI.setItem(8, Creator);
       
        ItemStack Tester = new ItemStack(Material.ICE, 1);
        ItemMeta Testermeta = Tester.getItemMeta();
        Testermeta.setDisplayName(ChatColor.AQUA + "Tested by Rand0mzxD.");
        Tester.setItemMeta(Testermeta);
        GUI.setItem(0, Tester);
    }

    public void onEnable() {
        Bukkit.getServer().getLogger().info("Drinks Enabled!");
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
        setItems();
         }
    }

    public void onDisable() {
        Bukkit.getServer().getLogger().info("Drinks Disabled!");
    }

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent event) {
        event.getPlayer().getInventory().clear();
        ItemStack Chest = new ItemStack(Material.CHEST, 1);
        ItemMeta Chestmeta = Chest.getItemMeta();
        Chestmeta.setDisplayName(ChatColor.DARK_GREEN + "" + ChatColor.BOLD + "Drink" + ChatColor.AQUA + "" + ChatColor.BOLD +  " Selector");
        Chest.setItemMeta(Chestmeta);
        event.getPlayer().getInventory()
        .addItem(Chest);

    }
    public static Economy econ = null;

    @EventHandler
    public void onInventoryClick(InventoryClickEvent e) {
       
        Player player = (Player)e.getWhoClicked();
       
       
        if (!e.getInventory().getName().equalsIgnoreCase(GUI.getName()))
            return;
        if (e.getCurrentItem().getItemMeta() == null)
            return;
       
       
        if (e.getCurrentItem().getItemMeta().getDisplayName().contains("Cola")) {
            e.setCancelled(true);
            e.getWhoClicked().getInventory()
                    .addItem(new ItemStack(Material.POTION, 1, (byte) 2));
            e.getWhoClicked().closeInventory();
        }
        if (e.getCurrentItem().getItemMeta().getDisplayName()
                .contains("Lemonade")) {
            e.setCancelled(true);
            e.getWhoClicked().getInventory()
                    .addItem(new ItemStack(Material.POTION, 1, (byte) 5));
            e.getWhoClicked().closeInventory();
        }
        if (e.getCurrentItem().getItemMeta().getDisplayName().contains("Vodka")) {
            e.setCancelled(true);
            e.getWhoClicked().getInventory()
                    .addItem(new ItemStack(Material.POTION, 1, (byte) 9));
            e.getWhoClicked().closeInventory();
        }
            if (e.getCurrentItem().getItemMeta().getDisplayName().contains("Created by KrypticIce.")) {
                e.setCancelled(true);
                e.getWhoClicked().closeInventory();
            }
            if (e.getCurrentItem().getItemMeta().getDisplayName().contains("Tested by Rand0mzxD.")) {
                e.setCancelled(true);
                e.getWhoClicked().closeInventory();
            }else{
                player.sendMessage(ChatColor.DARK_GREEN + "EquinoxNetwork" + ChatColor.DARK_AQUA + " >>> " + ChatColor.RED + "Please donate to gain access to these!");
    }
       
    }

    @EventHandler
    public void onPlayerRespawn(PlayerRespawnEvent event) {
        event.getPlayer().getInventory().clear();
        ItemStack Chest = new ItemStack(Material.CHEST, 1);
        ItemMeta Chestmeta = Chest.getItemMeta();
        Chestmeta.setDisplayName(ChatColor.DARK_GREEN + "" + ChatColor.BOLD + "Drink" + ChatColor.AQUA + "" + ChatColor.BOLD +  " Selector");
        Chest.setItemMeta(Chestmeta);
        event.getPlayer().getInventory()
        .addItem(Chest);
    }

    @SuppressWarnings("unused")
    @EventHandler
    public void onPlayerInteract(PlayerInteractEvent e) {
        Player p = e.getPlayer();
        Action a = e.getAction();
        ItemStack is = e.getItem();
        if(e.getPlayer().hasPermission("Drinks.OpenGUI"))

        if (a == Action.PHYSICAL || is == null || is.getType() == Material.AIR)
            return;

        if (is.getType() == Material.CHEST)
            e.getPlayer().openInventory(GUI);   

}
}

 

um you'd put if (player.hasPermission("Drinks.DrinkName") right before the part where it gives them the drink. where else?