Certain extended features of the DC Envelope Printer, are made permanently available or accessible, via purchases within the app. The process of purchasing one of these extended features, is called an in-app purchase.
If you initially downloaded the DC Envelope printer app when the app was made available for free, you will have to purchase the full database access feature, before being able to access and purchase the Notes and Logo features, as well as the Bulk Mail feature, and External Data Management (Export/Import) feature. To purchase the full database access feature, you will have to attempt to add more than 1 return address or address record, to the app's database, and respond to prompts to purchase the feature, while you are doing so.