According to the SFLC document consent only needs to be obtained if the permissive license is to be retained Re licensing of work already covered by a permissive license can be done without consent and is indeed done all the time Microsoft didn t ask anybody when they appropriated the BSD TCP stack and relicensed it as part of Windows I m skeptical that it even needs to be done in the cases the SFLC describes as that sounds more like a GPL induced requirement than one pertaining to permissive licenses which are far less restrictive