Learn how to make a inventory save and load using Save Game Pro.

Inventory.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using SaveGamePro;

public class Inventory : MonoBehaviour {

  public struct Item {
    public string name;
    public int amount;
  }
  
  protected Dictionary<string, Item> m_Items;

  void Awake () {
    m_Items = new Dictionary<string, Item> ();
    Load ();
  }
  
  void OnApplicationQuit () {
    Save ();
  }
  
  public void Pick (GameObject item) {
    if (m_Items.ContainsKey (item.name)) {
      m_Items[item.name].amount++;
    } else {
      Item value = new Item ();
      value.name = item.name;
      value.amount = 1;
      m_Items.Add (item.name, value);
    }
  }
  
  public void Save () {
    SaveGame.Save<Item> (m_Items, "inventory-items");
  }
  
  public void Load () {
    if (SaveGame.Exists ("inventory-items")) {
      m_Items = SaveGame.LoadDictionary ("inventory-items");
    } else {
      m_Items = new Dictionary<string, Item> ();
    }
  }

}