An indicator or display that may be in the form of a label that can instantaneously provide confirmation that a product is in a good preservation state by making a simple visual check, and particularly to detect if the product temporarily went outside a determined temperature range and to memorize this event. Strict monitoring of a temperature range is essential to be able to guarantee quality of many products. The indicator or display may be applicable to any product or device for which the temperature has to be monitored between two thresholds.