how to check rpm license without installing?

Command to find out installed rpm license information
   1) Find out the installed rpm name by running
       rpm -qa|grep -i <name-of-rpm>
       Ex: rpm -qa|grep -i post
             O/P: postfix-2.7.2-12.3.x86_64
   2) Query for additional information on that package, with below command
        rpm -qi <name of the installed rpm>
       It provides lots of information like Version, Description, License, etc. We can grep for required information like
        Ex: rpm -qi postfix-2.7.2-12.3.x86_64|grep "License:"
           O/P: Size        : 2685020                          License: IBM Public License ..

       As you can see the above command provided some extra information along with License. Is there a better way to do this? Yes.
        rpm -q --queryformat '%{name},%{version},%{license}\n' postfix-2.7.2-12.3.x86_64
       O/P: postfix,2.7.2,IBM Public License ..
       To fetch only license
       rpm -q --queryformat '%{license}\n' postfix-2.7.2-12.3.x86_64
       O/p:      IBM Public License ..

Command to find out rpm license information without installing it?
Now I assume you have the rpm file of your interest (Ex: postfix-2.5.13-0.17.4.x86_64.rpm). To know the licesnse information from it, run below command
rpm -qp --queryformat '%{name},%{version},%{license}\n' <rpm-file-name>
Ex:  rpm -qp --queryformat '%{name},%{version},%{license}\n' postfix-2.5.13-0.17.4.x86_64.rpm