The lasting effect of the Treaty of Versailles was World War II. This was the most important effect that this treaty had.
The treaty led very directly to WWII because it made Germany very unhappy. Germans were angry because they had been made to claim all the guilt for the war and because they had territory taken away from them. They were angry because they were prohibited from having a strong military. These things made the Germans bitter and resentful. Then, added to this, there were the reparations the Germans were forced to pay. This helped cause economic hardship in Germany.
All of these things led to a situation in which a person like Hitler could come to power. Hitler promised to avenge the wrongs done to Germany and Germans were willing to listen because of how unhappy they were with the treaty. In this way, the Treaty of Versailles led to WWII.