After you've checked the agreement to the EULA and click "Next", the installation does not proceed.
1) Do Windows >> Start >> Run - type regedit into the box & then click ok
2) Click on My Computer in the left panel, then File Menu >> Export to save a copy of your Registry. Do not proceed unless you have completed this step!
3) Navigate to HKEY_CURRENT_USER\Software\EvolutionComputing\CampaignCartographer3\SerialNum (for CC3) or HKEY_CURRENT_USER\Software\Slayton Sofwtare\FT3SerialNum (for FT3).
4) In the right hand panel right-click the entry and choose "Delete".
5) Restart the CC3 or FT3 installation.