With the price of PlayStation Plus going up in Europe at the end of this month, Sony is giving subscribers a reason to extend their subscriptions early by offering 15 months for the price of 12. You will be able to “stack” your existing subscription by 15 months for £39.99.
The offer is available only until 10am on 29th August, after which the price of a 12-month subscription will change to £49.99 permanently.
There is nothing stopping you from making use of this offer multiple times to extend your subscription by 30 or even 45 months, providing you have the cash to spare.