After you buy, you get a link. Sign in to your free Google account, click Make a copy, and the tool is saved in your own Google Drive.
No. One payment. Use it as long as you like.
Yes, in the free Google Sheets app. Setup is easiest on a computer.
You can download any copy as an Excel file (File > Download). Some features are made for Google Sheets.
Email wischavenindustries@gmail.com with your order number.