If done properly with proper oral hygiene considering you are asking about a permanent cement, it can last for 5-7 years or sometimes for decades.

Depends on the type and for what application- cements used for crowns, inlays or onlays may last indefinitely as long as the restoration is sound

There are many factors that determine how long the cement will hold. The design of the tooth under the crown plays a very big part in longevity. The bite plays a role also. All things being at their best the cement should hold a crown for 20+ years.