How does a judgement work and what happens when the 7 years are up?

Judgments are not good if you ever plan to have anything of value. The debt is probably on your credit report. Have you ever looked at yours? The judgment accrues additional interest at the legal rate, which varies state-to-state. The judgment is a lien against anything you own: land, cars, boats, furniture, bank accounts. The creditor can use the judgment to garnish/levy wages, bank accounts, and otherwise legally harass you until you pay. You can't sell or dispose of real property, whether purchased or inherited, until the judgment lien is satisfied (paid). Usually at the end of seven years, a creditor will renew the judgment.

Judgements work partially well. You don't say what side of the judgement you are on so its hard to answer how it would work for you.

A judgement allows you to use legal means to force payment. It allows you to garnish salary (in most jurisdictions), attach cash assets and possibly attach real property. The catch here is that you have to find where the person works and what assets they have. The court doesn't issue a blanket right to grab their assets.

Generally a judgement is renewable for at least one more term.