a method and apparatus are described which periodically sense environmental conditions , such as temperature , humidity , or voltage applied to a product , and apply these sensed measurements to models of ageing acceleration . acceleration factors from the models are accumulated in nonvolatile storage . the accumulated effective aging of the product is displayed to the owner or prospective customer in various desired formats , such as effective age , current acceleration factor , estimate of effective life used , or estimate of remaining life left in the product . a warning can be sent to the user to indicate that the product &# 39 ; s effective life is over or is nearly over .