UE4 Blueprint Library containing function to get Steam Session Ticket for use with Third-Party services like playfab or GameSparks

SteamHelper.cpp

// Fill out your copyright notice in the Description page of Project Settings.
// Replace YOURGAME with the projectname of your game 

#include "YOURGAME.h"
#include "Online.h"
#include "OnlineSubsystem.h"
#include "SteamHelper.h"

USteamHelper::USteamHelper(const FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)
{
}

FString USteamHelper::GetSessionTicket()
{	
	IOnlineSubsystem* OnlineInterface;
	OnlineInterface = IOnlineSubsystem::Get();
	FString SessionTicket = OnlineInterface->GetIdentityInterface()->GetAuthToken(0);
	return SessionTicket;
}

SteamHelper.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "SteamHelper.generated.h"

UCLASS()
class USteamHelper : public UBlueprintFunctionLibrary
{
	GENERATED_UCLASS_BODY()

	UFUNCTION(BlueprintCallable, Category = "Steam")
	static FString GetSessionTicket();
};