Playstation Now is a game streaming service from Sony that lets you play PS3 games on your PS4. You can either rent individual games or sign up for a monthly subscription. The subscription costs $9.99 monthly, but a 7-day free trial is available. Unfortunately, you can't play PS3 games on the PS4 if you don't have a Playstation Now subscription. However, you can still play old games from the Playstation Store or games from the PS4 Pro.