Since the iRule Editor is an open source project (the source is available on DevCentral), the license defaults to the license in the source.
//===========================================================================
//
// File : iRulerMain.cs
//
//---------------------------------------------------------------------------
//
// The contents of this file are subject to the "END USER LICENSE AGREEMENT FOR F5
// Software Development Kit for iControl"; you may not use this file except in
// compliance with the License. The License is included in the iControl
// Software Development Kit.
//
// Software distributed under the License is distributed on an "AS IS"
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
// the License for the specific language governing rights and limitations
// under the License.
//
// The Original Code is iControl Code and related documentation
// distributed by F5.
//
// The Initial Developer of the Original Code is F5 Networks, Inc.
// Seattle, WA, USA.
// Portions created by F5 are Copyright (C) 2006 F5 Networks, Inc.
// All Rights Reserved.
// iControl (TM) is a registered trademark of F5 Networks, Inc.
//
// Alternatively, the contents of this file may be used under the terms
// of the GNU General Public License (the "GPL"), in which case the
// provisions of GPL are applicable instead of those above. If you wish
// to allow use of your version of this file only under the terms of the
// GPL and not to allow others to use your version of this file under the
// License, indicate your decision by deleting the provisions above and
// replace them with the notice and other provisions required by the GPL.
// If you do not delete the provisions above, a recipient may use your
// version of this file under either the License or the GPL.
//
//===========================================================================
What are your concerns?
-Joe