Service life is the time period over which an asset is expected to be used. Service life is the basis for the depreciation of an asset, since depreciation only spans the service life of an asset. If there is a chance that an asset will become obsolete or fall into disuse later in its life, then its physical life may prove to be longer than its service life.
If an asset exceeds its service life, the manufacturer may refuse to support it. This situation arises because the manufacturer has not planned to retain service parts for such an extended period of time.