Some apps such as the Database Editor have Lite (free, limited) and Premium (paid, full) versions. Use the following chart to see which apps have Lite & Premium versions, and what is the difference.
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Application Version ​Description
Appointment Scheduler Lite 10 appt, no staff, no vacations, no SMS (when implemented)
  Premium All inclusive
Database Editor Lite Read Only (can’t edit DB, but can import/export)
  Premium All inclusive
Local Promotions Lite 10 active Daily Deals/ Gift Cards
  Premium All inclusive
Page Usher Lite Only browser-based redirects
  Premium All inclusive