"Veritas is my own version of Apple's Truth font, which is rumored to be the system font under Mac OS 8. Some people strongly dislike Truth/Veritas and prefer the font Espi Sans Bold 10 that prior versions of Aaron used. If you would rather use Espi, Greg's Buttons has system font substitution feature which overrides Aaron. If you use Greg's Buttons for the sole purpose of overriding Aaron's font substitution, you do not need to pay the Greg's Buttons shareware fee."
In this case, to get rid of Greg's Buttons' shareware message: just turn off the "Annoying Shareware Message" check box.
Another solution: The Veritas 12 font is a "private version embedded in the Aaron file itself." In this regard, Snerd Chong points out that you can get the Epsi font back in Aaron 1.6 by using ResEdit to copy the NFNT resource from an earlier version of Aaron and paste it into the new version, switching the ID resources.