Back in the early days of PSN, it was possible to log into someone elses PS3 and download a game from the Playstation store. You could then log out and the game would continue to work on the PS3. This could be done with up to 5 different accounts. Can the same thing still be done with the PS4?
PSN has had a major overhaul with the introduction of the PS4. One such feature to be abolished was the ability to share games with your friends. It is unfortunate, but also understandable. However, it is still possible to account share, but it is a lot more difficult to achieve if you are intending to share games with your friends. If you want to know more about how to account share with the PS4, check out the post about how the primary PS4 system works.
There are some security issues with account sharing in general and I would advice anyone who is thinking of this to carefully consider it. Making a PS4 that is not your own, the primary PS4 for your account, is a bad idea and can lead to trouble.