The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From Benjamin Zeiss:
Renewables allows you to manage items that are consumed on a regular basis and used up after a certain time (such as contact lenses, pills/medicine, office material and so on). You specify your current stock of the items that will be used up by specifying the amount you have, when you started using the amount you have and how often you consume your items. Based on the entered data, Renewables calculates how many days are left before your stock is empty and when that date will be. Renewables is integrated with the iOS Calendars and Reminders. You can easily add calendar or reminder entries to be warned early enough before your stock runs out.