Segments come in two kinds, and the difference matters for how you use them.
*The save dialog, where the Keep live toggle decides whether membership refreshes.*
You choose when you save: the Keep live toggle in the save dialog, described as "auto-refresh membership as consumers qualify". Saved segments show which they are in the list.
LIVE SEGMENTS
A live segment re-evaluates continuously against its definition. As consumers meet or stop meeting the conditions, they move in and out automatically. "First-time scanners (7d)" is a live segment — its membership rolls forward every day.
Use live segments for ongoing flows like welcome journeys or lapsed-consumer win-backs, and for anything whose definition contains a rolling window. A time-based condition in a static segment stops meaning what it says the moment you save it.
STATIC SEGMENTS
A static segment is a frozen snapshot taken at a point in time. Membership does not change after capture.
Use static segments when you need a stable list — everyone eligible for a specific draw, a prize audit you may have to defend later, or a control group for an A/B test where membership must not drift.
RULE OF THUMB
If you want the segment to always reflect "who qualifies right now", make it live. If you need a list that will not move under you, make it static.
One consequence worth knowing: exporting a live segment gives you its membership at export time, so two exports a week apart will legitimately differ.