Well, he agreed during the convention that he would help fight against Japan and he “promised” that free elections would be held in Hungary, Poland, Romania, Czechoslovakia, and Bulgaria. He promised both the pope and the U.S. president.
Turns out Joseph Stalin is not that great at keeping promises. He violated the rights of those countries by securing communist governments in the countries that were in his sphere of influence. In fact, I think the Soviets got the most out of the convention.
I think it revealed his true intentions.