Conjured items are inherently unstable and their binding energy dissipates over time. So conjurers quickly developed a way to detect this effect in order to be able to know when it makes sense to restore faded power into an item or when it is better to just create whole new item. At least until they are powerful enough to increase stability levels and prevent disappearance of the item alltogether.

See also: feel power level, see item stability, minor stability boost