If you are using MFA to authenticate user logins you can opt to allow users to mark devices / browsers used for login as trusted. This removes the need for the secod step of authentication for this device, for a specified number of days.
Activate the feature in system parameters by entering a number of days for device trust. Setting this to 0 disables device trust meaning that the second authentication step is required for all MFA logins.
Once the trust duration is set in system parameters, when a user next logs in they will be offered a checkbox option during login labelled "Don't ask again on this device for .... days".