depends on which continent your product is marketed
The MDD requires maintaining the quality records, DHF etc for 5 years after last device has been placed on the market.
However stating the 'life' of a device also limits the duration of maintaining the records. This also depends on the type of device and National legislation can also vary requirements, even within the EU.
Obviously Class III active implants have different requirements to low risk Class I devices.
The other fairly important issue is advising the Authorised representative (the EU Rep for non EU manufacturers), that the device has ceased to be placed on the market.
This can be done by adding an end date to the Declaration of Conformity. This means the CE mark is no longer placed on the device and legal requiremnt for conformity with the Essential Requirements ends.
However the need for post market survellance does not end nor does vigilance. This could be another advantage of stating the intended service life of the device.
Other countries / regions have varing rules depending on the device risk classification.
Hope that helps - CELEO