TBB and other open-source software available from this site is licensed  under GPLv2 with the (libstdc++) runtime exception.  Specifically, the TBB open-source license is the same license used by the GNU libstdc++ library in gcc 4.2.1 (and earlier).  For a complete description of the license, please visit the official GNU website for GPLv2 and for the runtime exception. 

See the TBB FAQs for more information on TBB open-source (and commercial) licensing.