@Moon Then please be sure that you use GPL as the license for the project codes. For example, Gnuboard is not actually affiliated with the GNU project but its license is GPL so people can use Gnuboard just like other GNU software.
However, Gnuplot license actually conflicts with GPL so it can be malicious that if an user expects that Gnuplot's license is GPL like other GNU software, then he will be disappointed or troubled when he find actually it's not.