Enklast direkt från tillverkaren:
http://www.projectpluto.com/faqnew.htm#OrderingVäldigt generöst licensavtal, finns även en yahoo grupp för programet:
How is Guide 9.0 licensed?
Guide 9.0 is distributed under the GNU General Public License. This basically means you can use the software as you wish, including making copies for anyone you wish. (There are some limitations -- GPL doesn't mean "public domain" -- but the limits are not nearly as severe as with "normal" software licenses.)
Therefore, if you wish to purchase a copy and make duplicates for your school, astronomy club, neighbors, etc... go ahead; it's legal.
h-g