djkym, SQL Server Express, is just a free version of sql server. The purpose of SQL Server Express is to allow developers to get their product to market WITHOUT requiring additional costs to end users who don't require full blown sql server. The database file (.mdf) and the log files (.ldf) are identical and can be DETACHED FROM ONE SERVER TO ANOTHER.

ALL I repeat ALL AC4 has to do is to ALLOW THE USER TO SET THE DATABASE CONNECTION STRING AND WRITE THAT SETTING IN THE
APP.CONFIG FILE!

This will allow the users to store their databases where ever they want on ANY SERVER they want.

"The illiterate of the 21st century will not be those who cannot read and write, but those who cannot learn, unlearn, and relearn." ~ Alvin Toffler