Individuals who are enrolled in one of U.S. immigration's trusted traveler programs like NEXUS must generally update any information that has changed since they submitted their application for the program.
According to an informal conversation with a local CBP officer, an individual who possesses a NEXUS card must update their NEXUS account each time they receive a new I-94 card. The NEXUS card's travel authorization is tied to each unique I-94 card number.
This is particularly important for TN visa workers who have renewed their TNs, filed a TN application to chage employers, or otherwise have received a new I-94 card. Such instances may trigger a requirement for these individuals to update their NEXUS account.