There is a way forward. You may not be able to redistribute certain free unpackers, but the end-user can legitimately obtain such unpackers and add them to the Univeral Extractor\bin\ directory. Universal Extractor could detect the presence of these user-supplied unpackers, and then offer the appropriate upgraded functionality. The installer for Universal Extractor could leave behind a text file offering instructions on how to obtain the optional extras for the \bin\ directory.