Warning: There are spoilers ahead for Back in Action.Matt (Jamie Foxx) lies to Emily (Cameron Diaz) about the ICS Key for an important reason in Back in Action. The ICS key is the movie’s Macguffin, which has the ability to manipulate any electronic system. Matt and Emily’s CIA jobs require them to locate the ICS Key before it is seemingly lost during a plane crash. The fate of Back in Action‘s ICS Key remains unresolved for fifteen years, during which Matt and Emily get married, have two children, and build a life that has nothing to do with espionage.

https://screenrant.com/why-matt-lied-to-emily-about-ics-key-back-in-action/