When someone purchases a font, they don’t own the font per sé—only the right to use it. Rights are specified by an End User License Agreement [EULA]. Violation of the EULA by a patron constitutes grounds for revocation of the license and, for infringement of intellectual property, federal prosecution in the US and other countries of origin.
It is the Partner’s responsibility to determine the rights to be granted, to compose documents expressing them and to associate the appropriate EULA with each font. Example issues: