There is a feature reduced Open Source version released under the SugarCRM Public License, which is identical to the Mozilla Public License with the Red-Hat like addition that the logo and name are trademarked by SugarCRM and are not licensed.

All of that is very nice and it appears to be a nice product.  They also release a professional version with more features, which they sell.    They are featured in an EWeek article (top of first internal article page) on page 9 of the 8 Aug 2005 dead tree edition.  I cannot find it on EWeek's website at this time.  The EWeek article made me go looking at it more closely because we are not happy with our current consultant created CRM.

However, in looking at their professional version so that we might get some of the features, I glanced at their commercial license and was shocked by a clause in section "1.2 Restrictions":

1.2 Restrictions.

During any term of this Agreement, Company shall not, directly or indirectly:

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(iv) use or run on any of Company's hardware, or have deployed for use, any copy or version of the SugarCRM open source version of the Software;

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I will note that even the commercial version allows you access to source code (though there are encrypted portions mentioned) and allows you to modify it for internal use.

The commercial version is licensed on a per seat basis.  So, presumably, they don't want you paying just for seats that need the commercial features.