Problem with Soomla In-app purchase

i want use Soomla in-app purchase in unity 5.3 but when first lifeTimeVg purchase finish , after that my app crash (in Initializing) and dont run again or after payment for SingleUseVG app crash. i saw similar problem in questions but didn't find any answer. anyone have answer for that? do that relate to my unity version? my soomla store version is 1.7.7

this is my items for purchase:

   using UnityEngine;
   using System.Collections;
   using Soomla.Store;
   public class ItemsForPurchase : IStoreAssets{
   public const string  removeAd = "removeAd";
   public VirtualGood[] GetGoods() {
     return new VirtualGood[] {  ADS_Remove };
     }
     public int GetVersion() { 
           return 0;
     }
 
     public VirtualCurrency[] GetCurrencies() 
     { 
         return new VirtualCurrency[]{};
     }
     public VirtualCurrencyPack[] GetCurrencyPacks()
     {
         return new VirtualCurrencyPack[] { };
     }
     public VirtualCategory[] GetCategories() {
         return new VirtualCategory[] { };
     }
 
     public static VirtualGood ADS_Remove = new LifetimeVG("No Ads",
         "No Ads In Game"
         , removeAd,
         new PurchaseWithMarket(removeAd, 2000)
         );           
 }
 

And this is my another class for manage social media:

 using UnityEngine;
 using System.Collections;
 using Soomla;
 using System;
 using Soomla.Store;
 public class SocialMediaController : MonoBehaviour {
 public static SocialMediaController instanse;
 private VirtualGood[] goods = null;
 private ItemsForPurchase items;
     
     void Start()
     {
         if (instanse) {
             Destroy(gameObject);
         }
         else {
             instanse = this;
             GameObject.DontDestroyOnLoad(gameObject);
             items = new ItemsForPurchase();
             goods = items.GetGoods();    
            StoreEvents.OnItemPurchased += onItemPurchased;        
            SoomlaStore.Initialize(items);
           // for run one time intialize , i put it here
         }
     }       
     void OnItemPurchased(PurchasableVirtualItem pvi, string payLoad)
     {
         print(pvi.ItemId);   
     }
     public void Buy() {      
                 VirtualGood item = goods[0];           
                  StoreInventory.BuyItem(item.ItemId);                        
     }
 
 }
 

also I see OnItemPurchased wont call. Thanks if help me :)