Android/IOS simple app - repost

We have a small web-shop and we would like to build a simple app for our costumers for android and Ios. The products that we sell require consumable items, and we would like to offer our costumers a small app to remind them when to purchase and change consumable items. We will discuss the project in detail with the selected candidate but the app should have a simple calendar based reminder where the costumer can include the purchase/installation date and product model and the app will automatically set an "alarm" for different consumable items. In addition when the reminder will pop-up the costumer should have and option to order new replacements with one touch of a button. The order he will place should reach our e-mail address. Very Important: The costumer should offer free tech support for patches and updates in the first 6 moths from the completion of the app IF bugs appear to the app.