Maintenance for the week of November 18:
• PC/Mac: No maintenance – November 18
• ESO Store and Account System for maintenance – November 19, 9:00AM EST (14:00 UTC) - 6:00PM EST (23:00 UTC)
• PlayStation®: EU megaserver for maintenance – November 19, 23:00 UTC (6:00PM EST) - November 20, 17:00 UTC (12:00PM EST) https://forums.elderscrollsonline.com/en/discussion/668861
I've been digging around online for an answer, and everything I've found points to the PSN store. After you buy the initial subscription to ESO +, the "buy" button changes to an "extend" button on the store page.
Unfortunately, you cannot buy many months in advance on PS4. Only one month at a time. After your first month runs out you just buy another month. If you have a credit card on file with the PS store, then it will auto-renew.
There is no way to pay in advance for like a six-month subscription on PS4. Only one month at a time.
It automatically renews every month from start date. Been a member for a year now. But make sure you have money in the bank by the date they charge you. I had to pay a 1300.00 credit bill and it left me with like 8.00 in my bank account and they charged me the next day which went unnoticed until the overdraft charges went up to about 200.00 lol. Just be careful but it's quite rewarding.