Microsoft Office Accounting Express 2008 is a free accounting software which can be upgraded to a more feature rich and full feature complete Microsoft Office Accounting Professional 2008. Users can also download and request a free product key to use MOA Professional 2008 as a trial or evaluation for 60 days. The Professional and Express editions are essentially the same installation which its functions accessible to users are determined by the product key used.

However, at the end of the trial period, Office Accounting 2008 will force users activate and register the software online or by phone without a chance to change or reset the trial product key to newly purchased licensed serial product key, or in the case of deciding not to buy, to downgrade and revert back to Office Accounting 2008 Express version, which supposedly to be always free of charge.

With the old product key used for activating, the results are always rejected and forced to quite due to invalid or expired key, rendering users unable to use the Office Accounting 2008, and even the free Express edition. As the same configuration is used for both OA 2008 Professional and Express, uninstall and reinstall downloaded Express setup installer does not help. The program will still picks up existing used product key and attempt to activate with it without prompting users to change key or option to downgrade to Express edition. The similar situation also applies to users who use illegal Professional edition product key leaked on the web or downloaded from BitTorrent, eD2K or other warez and crack sites.

The workaround is to reset the product key of Microsoft Office Accounting 2008 entered, and then re-enter a new product key, or in the case to revert to use the free Express version, use the default Express product key supplied in the first time usage activation wizard.

To reset the product key, firstly uninstall the Microsoft Office Accounting 2008 Express or Professional that is currently installed. Uninstallation can be done from “Add and Remove Programs” (XP) or “Uninstall a program” (Vista) in Control Panel.

Then, open Windows Explorer, ensure that Folder Options’ View configuration (under Tools menu in Windows XP or Organize menu in Windows Vista or Windows 7 or View menu in Windows 8, Windows 8.1 and Windows 10) has set to allows users to view hidden files and folders. Then navigate to the following path:

C:\ProgramData\Microsoft\Office Accounting\3.0\ (for Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10 or later)
C:\Documents and Settings\All Users\Application Data\Microsoft\Office Accounting\3.0\ (for Windows XP)

Delete the pa.dat inside the directory.

After deleting the “pa.dat” which stores product key, activation and registration information, reinstall Microsoft Office Accounting 2008 Express or Professional. On first run, the activation and registration wizard will run, providing the default free product key for Express edition. If you have bought a license for Professional edition, enter accordingly.