That deal is pretty much the standard deal in terms of extended support. Here's what I mean....when we bought Win 7, the agreement between us and Microsoft was ... Microsoft to support the OS until 2020.
In my work I deal directly with Microsoft.
For Windows 7, mainstream support ended in January of this year. This just meant that they do not sell it any more, that requests for design changes and future major releases ended, and that their "extended support" kicked in on that date, which lasts five years.
Microsoft confirmed to our agency that mainstream support for all versions of Windows 7 ended then. But users continue to receive free security updates under their extended support until January 14, 2020. The quote Microsoft gave out in that regard was this:
Microsoft said:Extended support lasts for five years and includes security updates at no cost, and paid hotfix support. Microsoft will not accept requests for design changes or new features during the extended support phase.
My guess is that this is what you company is talking about. It's pretty much the same for everyone.
Now, a person can pay Microsoft a lot of money (if they are a big enough customer) to purchase custom support in the form of paid for personnel to maintain things even longer...but that is rare, and only for specific, very high level customers.
Most people who do not absolutely have to, do not do so, because it ends up putting them further and further out of date as a corporation as a whole.