>>So Microsoft, the vendor, scammed me?<<
If this is a purchase via the Workplace Discount Program (previously called the Home Use Program), then it would be legitimate. You can reinstall from the Order History page at https://www.microsoft.com/en-us/workplace-discount-program/order-history if necessary. Office products obtained via the program are only valid for as long as you are with the employer that provided you with the license, though.