Running backup server on temporary license?

I have a customer that has a simplex (non-redundant) license. They have a backup Ignition server that currently only has the 2 hour temporary license. They are interested in upgrading Ignition on the active (master) node from 7.9.3 to 7.9.9, thinking that they can run on the backup for 2 hours while upgrading the master. Would this work?