Yes, There are ways for backup license server.You can user one of the following methods:
1) Duplicating the license server and its contents. Give the duplicate computer the same name as the active license server and store it off the network.
2) Storing an additional license server on the network with a different server name. In this case, when the active license server fails, you need to change the backup server name to start using it as the active license server.
3) Creating a clustered license server