Commercial distribution of chemfp started with version 1.1, which was released in February 2013. The no-cost version is also version 1.1, so you could just start with that. Over time, the commercial version will gain new features first, and the free version will be at least one and likely several years behind.

If you are interested in purchasing a chemfp support contract or funding chemfp development, kindly send an email to sales@nulldalkescientific.com.

License

The commercial distribution of chemfp is provided under the MIT/BSD license or a similar permissive license. The license details and list of copyright owners are listed below.

Library for working with cheminformatics fingerprints

Unless otherwise noted, the chemfp software is distributed under the 
terms of "the MIT license" which follows:

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Permission is hereby granted, free of charge, to any person obtaining 
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

=====================================================================

The maintainer and primary copyright holder is
 - Andrew Dalke, Andrew Dalke Scientific AB

Other copyright holders are:
 - Kim Walisch, <kim.walisch@nullgmail.com>
 - Stanford Univeristy (written by Imran S. Haque <ihaque@nullcs.stanford.edu>)
 - Python Software Foundation (the heapq code)

This package also includes (nearly) unmodified copies of
 - chemfp/progressbar/ by Nilton Volpato under the LGPL 2.1 and/or BSD license
 - chemfp/futures/ by Brian Quinlan under the Python license
 - chemfp/argparse.py by Steven J. Bethard under the Apache License 2.0