The Office On Demand deployment of Office 2013 is not compatible with our software. Office Web Apps (now called Office Online) have a different architecture from Excel and do not support Visual Basic for Applications, which is needed by our add-ins. Microsoft advises us that you should contact Microsoft directly for assistance in changing any of those into a deployment that is compatible with add-ins. However, there is also an article on Microsoft's Web site: How to Get the Full Installation of Microsoft Office 2013.