Activate your PS4™ system as your primary system, using your account. Your PS4™ system can automatically download content you pre-ordered, or content you've purchased on (PlayStation App). ... You can connect to your PS4™ system via the Internet using Remote Play on another device.

What happens if I activate my friends PS4 as primary?

Benefits of activating a PS4 as Primary:

Anyone who uses your Primary PS4™ system can enjoy applications you purchase from the PlayStation®Store. Other users on the system can also enjoy some PlayStation Plus benefits from that account (like online multiplayer), even if that user is not logged in.

What does making primary PS4 do?

When you set a primary PS4, all other users of that PS4 can enjoy the digital content you own, even if they are not logged in to your account. For example, I buy Minecraft. My brother can then log into his account and play the game, even though he never bought it.