https://www.theverge.com/2018/10/2/17929996/surface-all-access-payment-plan-explained-office-365-microsoft

Microsoft is trying to make it simpler and cheaper — up front, at least — for customers to buy into its Surface lineup. It’s launching a new payment option called Surface All Access that, for a monthly fee, will give customers a Surface device and access to Office 365.

But while this sounds like a subscription service, it’s not. In reality, Surface All Access is just a well branded payment plan. So unlike a phone upgrade program, you don’t trade in the Surface devices for better ones later on; you keep paying month to month until you finally pay off the purchase after two years.