The proverb means that the effect of telling lies extends into the future. Or the lie we tell today, will have an adverse effect on us in the future. I have also heard the saying that
You would have to tell a thousand lies in order to defend a lie you previously told.
If you tell a lie to day, you would have to live the rest of your life telling more lies to defend it. If you lie today and you dare to tell the truth tomorrow, you will set contradiction in motion and people will take you for a liar. The proverb warns against lying.