read,open .db7 files - nexusdb or whatelse?

Hello guys, i've got a bunch of files with DB7 extension, coming from a customer's software. Each one of them is related to a database table. What I want is to export data in a more practical format, such as CSV.

Reading the header of the file, something addressed me to NexusDB, but I can't manage opening these files. Do you have any suggestions about that?