@GeorgeTheDev_1 My IAP’s are working now, Here how :
- Add IOSEngine File (Path : ProjectDir/Config/IOS/IOSEngine.ini)
[OnlineSubsystem]
DefaultPlatformService=IOS
[OnlineSubsystemIOS.Store]
bSupportsInAppPurchasing=true
bUseStoreV2=true;
[/Script/IOSRuntimeSettings.IOSRuntimeSettings]
bEnableGameCenterSupport=True
NOTE : Do check in iOS Project settings that GameCenter in enabled.
- Add Dependency in [ProjectName].Build.cs (If C++ Project)
PublicDependencyModuleNames.AddRange(new string[] { "OnlineSubsystem", "OnlineSubsystemUtils" });
if (Target.Platform == UnrealTargetPlatform.IOS)
{
	PrivateDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "OnlineSubsystem"});
	DynamicallyLoadedModuleNames.Add("OnlineSubsystemIOS");
}
- 
In Game Start Call ShowExternalLoginUI
- 
IAP Event (Execute in same sequence) 
 Read In App Purchase→Start In App Purchase→Finalize