The software can't use the OpenType fonts installed on your Windows 7 because the Label Factory Deluxe already has implemented proprietary fonts. This means that you don't have the possibility of installing custom fonts (TrueType or OpenType).
If you need additional fonts, access the official website and get in touch with the support team. They should provide all the necessary information to add their fonts or to buy others that are compatible with the application.
Contact support: http://www.novadevelopment.com/support/customer_service/index.html
Be aware that the support request also costs money.