What this meant was that the elderly person or couple, the pensioner(s), would give their land and the associated rights and obligations to a younger person in return for material support and services. So, for example, an elderly couple would hand over their land to their son, essentially allowing him to inherit before their deaths, in return for a place to stay (usually in the house with a spot by the fire), stipulated amounts of food, fuel, and clothing, the use of certain household goods,* and services like having their clothes washed regularly.
Most of these people were not inclined to leave things to chance. They were very specific about what the contract entitled them to. There was, though, a lot of variation in what that was and the more land a person had, the more they could bargain for. Someone with 20 acres of land could go so far as to demand that an entirely separate cottage be built for them, while someone with only 2 or 3 might have to offer to work for as long as they were able to. These things tended to be well enforced in the manor courts, with punishments for not providing the stipulated goods and services ranging from simple fines to the return of the land to its earlier owner, who could then make a new contract with someone else if they so wished.**
Before the 14th century and the plague, most of these contracts were made between family members. Pensioners were far more likely to be single people than couples and they usually, though not always, made contracts for themselves rather than letting someone else do it. They gave their land most often to single men, but sometimes to couples and occasionally to single women. The number of contracts made with family members dropped dramatically with the advent of the plague. Suddenly, people couldn’t count on their families to still be alive to care for them in their old age. They did, however, have a way to ensure that someone would.
*Bed linens and the like, for example
**Of course, we only have the evidence of cases that actually made it to the courts. Someone with less land and therefore less bargaining power was probably much less likely to make it to the courts.
Clark, Elaine. "Some Aspects of Social Security in Medieval England." Journal of Family History (1982): 307-320. [Can be found online here.]
Gies, Frances and Joseph Gies. Marriage and the Family in the Middle Ages. New York: Harper & Row, 1987.
Hanawalt, Barbara. The Ties that Bound: Peasant Families in Medieval England. Oxford University Press, 1986.