Confirmed with 5.12 beta 5 FREE edition too.
explanation. The .db files are on the ENTERPRISE version the embedded databases (SQLite database) used by the 'autocomplete' feature. The name is a checksum of connection details. One file is created each time you open a new connection.
The file does not make sense in FREE editon, and should not be in root folder!
If it is necessary to have such an empty file for for each connection with the FREE edition then they should go in a /TAGS folder like with the ENTERPRISE version.