Why not keep using the Microsoft Store edition?

The
Microsoft Store works just fine. The universal license has no benefit to you if you are able to install software from the Microsoft Store.

If you have purchased FileBot from the Microsoft Store, then your purchase / license is stored in your Microsoft Account. You will not receive a separate universal license. Please read
FileBot Pricing Explained for details. But, if you want a
complimentary 1-year universal license, then you're late, but we can make an exception for you.