I have lines by which I determine that the player beats the resource

 

     object OnDispenserGather(ResourceDispenser dispenser, BaseEntity entity, Item item)
        {
            if (!entity.ToPlayer()) return null;
            BasePlayer player = entity as BasePlayer;
            string name = player.displayName;
           if (dispenser.gatherType == ResourceDispenser.GatherType.Tree)
           {
           
                ShowUI(player, "Есть шанс получить семя дерева");
                int rng = Oxide.Core.Random.Range(0,100);
                if(rng == 1)
                {
                TreeConfig tree = _config.FindItemByName("Семя дерева");
                Item items = CreateItem(tree.Name,"seed.hemp", tree.Amount);
                player.GiveItem(items);
               
                }
           
           
           }
How can I make memorization of one tree, that is, I want to draw a CUI while the player beats one tree, and if he killed him or stopped beating him, then the CUI simply disappears