This actually depends. If the program is a spooler then its installing in the correct location (that is var/spool). If not, then you should change it.
Also about opt vs var/opt generally in modern systems, the root directories (/run,/opt etc) and their "var" counterparts (/var/run,/var/opt) are treated as equal, and in many distros they are actually linked to one another.
So its pretty much your choise. Personally i choose to install under /var because many servers have it mounted on a different disk for data security and redundancy and i would like to make their life easier!