Using Windows.Services.Store namespace to offer Free Trial to Licensed version purchase for Win32API/C++ app (MSI,EXE) in the Partner Center

UPDATE:

I have finally come to understand that I CANNOT use the MS Store payments system for an EXE or MSI distributed application !!?!?!?

I have spent the last few weeks getting my system ready and on the store, it has been a huge amount of work - but now It is all set and ready to go

EXCEPT I did not realize that an exe/msi distro can't actually update from Free Trial to paid via the store, and I'm not typically a complainer - but maybe that COULD have been made clearer within the documentation ???

In any case - I can create an MSIX package, however, I CANNOT re-use my application name and I really don't want to delete the current package and start completely over because I'd like to retain the existing store presence which was a lot of work to put together

Can someone somewhere release my app name CursiVision so I can re-user it in a new package

.... PLEASE ...

(My original question is below)

I cannot get the sample code to work to test the ability for customers to purchase the update for the Free Trial of my software (CursiVision) which is already hosted on the Microsoft Store and ready to go.

The Store (.cs) sample in the UWP samples throws "unexpected error" when I try to associate it with my product (first step fails: Reserve Name). I also cannot find out where in the partner center to reserve an app name so that the "list" of them would populate in the "Associate your app" wizard.

The Store (.cpp) sample fails to compile with: x:Class type 'SDKTemplate.Styles' is not found in 'SDKTemplate' I am not at all familiar with C++/XAML

It is NOT clear whether my product in the store MUST be UWP, OR, if the snippet of code that accesses the licensing MUST be UWP AND that that code must be in the application itself.

If I'm not able to integrate with the licensing with C++/Win32API, then I am hoping I can fall back to writing a small executable that handles the licensing and "launch" that from the product itself. That product is a huge, and I repeat C/C++/COM/Win32 API - there is no way I could convert it to UWP.

Anybody have sample code in C++ to integrate with the MS Store licensing ?

Thanks all for taking the time to help