Churn rate measures loss: the proportion of members who were active at the start of a period and are no longer active at the end. Definitions vary with the program, since a subscription can measure churn precisely at cancellation while a points program has to infer it from a member going quiet. However it is measured, churn is the leak in the program, and its rate sets how fast the base drains without new acquisition.
Consider a program that adds members steadily but loses a similar share each year to disengagement. Growth stalls because acquisition is merely replacing the churned, and the expensive work of signing up new members buys no net gain. Cutting the churn rate even slightly changes the arithmetic, letting the same acquisition produce real growth.
For an enterprise operator, churn is where loyalty economics are won or lost, because retaining an existing member costs a fraction of acquiring a new one. The value of predicting churn early is time to act, so programs invest in engagement signals and win-back mechanics that catch members while they are cooling rather than after they are gone.
