sell-by date
/ˈselbaɪ/noun
1- chiefly Brit. a date marked on a perishable product indicating the recommended time by which it should be sold〈主英〉（易腐产品上标明的）销售限期, 保质期：
crisps past their sell-by date.
过期的炸土豆条。
1.1
- informal a time after which something or someone is no longer considered desirable or effective〈非正式〉（人或物的）不再有用的时期; 无用时期：
do broadcasters have a sell-by date?
广播公司会有一天不再有用了吗？