system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: when you buy a burial plot do you purchase it forever? If so, how do graveyards remain profitable? If not, what happens to your remains?
gpt
In the UK when you buy a plot you have a lease on it. Usually for at least one hundred years, often longer.  So until at least one hundred years after the last person is buried in the cemetery all the graves remain intact. It is often longer. Eventually the graveyard will be left to get overgrown.  In cities where the land is valuable graveyards are sometimes redeveloped. When this happens all the graves are dug up and any remains are moved, often interned in one or two graves.   
Graveyards are usually owned by the church or local council so profit is not a factor.