They abandoned their products once the growth stopped and/or switch to subscription and gave their one time purchase makers a year of subscription to make it up.
One time payment for lifetime support doesn't make sense whatsoever. If it is a large company they have to employ people for a product that doesn't bring in money and for indies it means that they need to switch context from their current project, study their code and try to remember what they did and why they did it to fix a single line code.
Having a live product is a full time job even if you change a single line of a code once in a while. It's fine doing it for fee(in other words on your parents dime) when you are a teenager or when it is a passion project, otherwise its abandonware or your life destroyer(which is abandonware with delay).
Other options exist of course, like giving away the product for free then selling its control to people with other motives(widespread among browser extension developers) or sell services around the product like cloud something AI something (this one is nice actually, just not applicable to all apps).