Yes, you did pay for it. I've paid for multiple cars over the years, too, and they also needed to be replaced.
A perpetual license doesn't mean you can use the software for all eternity. One of the developers at 1Password explained it very well (paraphrasing a bit here).
A perpetual license means you can install that software on any computer and OS combination it will run on. The serial number will always work. It doesn't mean you will get free updates or upgrades on that purchase forever.
MS gave users a very generous eight years of updates on Office 2011. From Snow Leopard, all the way through High Sierra. That's a lot of work with no pay to cover their expenses. Programmers don't work for free, among all of the other daily expenses for a business.
2011 is not just 32 bit only software, which will not run on Catalina or later (they require all software to be 64 bit), but MS dropped all support for it last fall. They've even shut off the activation servers for it. Office 2011is dead. Obsolete.
MS changed the system requirements for the Mac a couple of years ago. Instead of constantly patching older titles so they'll run under numerous versions of the Mac OS, perpetual license versions, from their release date now run under three major Mac OS releases. Period.
Per MS' three year rule, Office 2016 (no longer sold) will only run under El Capitan 10.11.x through High Sierra 10.13.x. Office 2019 will only run under Mojave 10.14.x through Big Sur 11.x. Because Big Sur is the three year cutoff for 2019, Office 2021 (or 2022, whichever MS calls it), will be released in conjunction with macOS Monterey this fall since Office 2019 will not run under it.
If you require Office, and you want a perpetual license rather than the 365 subscription, the cheapest option is to get the single user license of 365 now and pay for it $6.99 monthly rather than for a year. Then as soon as Office 2021/2022 is released, purchase that and cancel 365.