The method using which Sentinel RMS provides License Manager backup is by creating the redundant License Managers setup. All the designated License Managers are grouped together to form a pool so that the next License Manager can take over when the primary License Manager (leader) goes down. As a result, the in-use licenses are not lost and continue to be served seamlessly by the new leader License Manager.
If the primary License Manager (the old leader) comes up, it reclaims leadership and the control is transferred back to the primary License Manager.
We recommend you to read through the following to understand redundant License Managers: