In-App Purchase Trigger

Hi,

My app checks to see if a text file has the value “Yes” or “No” in it and it is located in the “sand box”.  If it has “Yes” then I unlock certain features in the app.  When I roll this app out it will be free and then the user can press a button and purchase/unlock the features.  This is the first time that I am setting something like this up and I wanted to make sure that I understood the best way to do this so that if someone replaces their device in the future, that the store would be able to automatically check their purchases and download what they have purchased.  My questions:

  1. Can I upload a text file to the store

  2. Can the store download the text file with the “Yes” in it when requested to purchase a product or if the purchase needs to be restored

  3. How/when can I upload the text file

  4. Is this the best course of action or is there a better way to handle this

Thank you for you help!