Good news for the critics of Windows Genuine Advantage (WGA) and Office Genuine Advantage (OGA) is that Microsoft has quietly retired OGA. Office Genuine Advantage is a tool that will validate Microsoft Office whenever new updates, templates etc. are downloaded and installed.
Knowledgebase KB917999 from Microsoft confirms that Microsoft has retired the OGA tool but still they give the benefits of using genuine Office. If you have Office Genuine Advantage tool installed on your computer, you will get an error message when you try to validate your Office installation:
Error code: 0x8018111
Why didn’t my computer complete validation?
These errors will disappear when you validate your Office installation again after update.