changing computers


I need to install my Home & Business 2013, upgraded (probably over the internet) to H & B 2015, on a new computer running Windows 11.

I have the 2013 disc, 2013 Installation Key Code and the 2015 Installation Key Code.

Questions are:

  1. which Installation key do I use when installed, 2013 or 2015.
  2. if it is 2013 do i need to upgrade to 2015 again, and if so, how is it done.
  3. will my current files run on 2013 if it cannot be upgraded to 2015