Can anyone confirm if the Intel Parallel Studio XE (Composer Edition for Fortran & C++, 2016) includes a licence to release commercial software using Intel MPI? Or would I need to purchase a separate Intel MPI Developer Licence for this?
Since the Composer Edition doesn't include Intel MPI, your question is not answerable. Intel developer tools purchased with a Commercial license don't require run-time licenses and have no restrictions about commercial release. You can read the EULAs here - https://software.intel.com/en-us/articles/end-user-license-agreement I note that Intel MPI uses a different (and much simpler) license than Parallel Studio XE.