If you own a valid license for a newer Yamicsoft product (e.g., Windows 10 Manager), note that your key does not work for v2.1.4. Your best legal path is to purchase a used copy of Windows 7 Manager from a reseller or rely on the 30-day trial period for one-time maintenance.
This is where the article pivots to the gray area. The term (a portmanteau of "Key" and "Keymaker" from The Matrix franchise) refers to a program that generates valid license keys or patches the software to bypass trial restrictions.