How do I manage my PlayStation Plus membership? | PS4

https://store.playstation.com/en-us/grid/STORE-MSF77008-PSPLUSMEMBER/1

Managing your PlayStation Plus membership on a PS4 system couldn’t be simpler. See the expiration date of your subscription. Extend it by purchasing additional months of membership. Adjust settings for automatic subscription renewal. All of these options are easy to find on your PS4 system. Learn more about the benefits of PlayStation Plus membership here: https://support.us.playstation.com/articles/en_US/KC_Article/PS-Plus-Information

Source: Playstation YouTube