What I'm mostly curious about is if a King of say France in the 1200s sent an abbey some gold ducats (or whatever they used in france in the 1200s) for "perpetual prayers" doesn't that mean prayers forever? So would the abbey still be doing it today (assuming it still existed) or does it stop at some point? The nature of time means many of these abbeys may have been destroyed, especially in part of europe that turned protestant and obviously they will have stopped praying for people who died centuries ago but if the abbey still exists do they still do it? Or at some point does whoever is in charge stop caring about a guy that died centuries ago and stop?

Perpetual prayers. It was a thing for European Catholic rulers/nobles/rich people to leave money to specific monastries/convents/churches on their death for "perpetual prayers" for their soul. I assume anyone who did this in my own country (UK- England specifically) no longer gets them since the reformation but in parts of Europe that remain Catholic do they still pray for someone who died centuries ago? If not when did this stop?