CRM 4 License key matrix

Tried upgrading the Trial version and received this error.

Upgrading from a trial version to full version was such a production. There is an upgrade matrix available, I found after a few clicks on the web. Simon Houston put forth the CRM 4 License Key upgrade matrix which clearly explains which version of CRM can be upgraded. If you do not find a relevant upgrade intersection, you have just one option left "Re-install CRM 4" from scratch.