You need one license per server. Setup is the same as a regular installation, the only thing to note is that you should not replicate the /usr/local/fop2 directory where the fop2.lic file is installed (as the license will work only in their respective machine).

But you can replicate a configuration directory and move fop2 config files to that directory, then you can set the configuration directory via the -c command line in fop2.

Suppose you have /etc/asterisk replicated with drbd.. create a fop2 directory there ( /etc/asterisk/fop2 ). Then copy all the contents from /usr/local/fop2 into that directory, except for fop2_server and fop2.lic. Finally modify the fop2 init script /etc/rc.d/init.d/fop and specify the config dir in the options line (OPTIONS="-c /etc/asterisk/fop2 -d")

That will let you have a licensed fop2 on each machine on the cluster, sharing the configuration directory.

Best regards,