The only safe way to use Calibre on more than one PC might be to store it on a local USB drive. I'm not sure. A network drive or NAS even for one user at a time is a bad idea. A networked database used by more than one user / application program at the same time when it's single user like Calibre is a total disaster waiting to happen. You need a remote database server that's multiuser (Maria, MySQL, MSDE, MS-SQL, Oracle, DB2 etc, not SQLight, Access or similar set of files accessed directly by the application, and the application has to be somewhat aware. AFAIK Calibre doesn't support a database server API, it's single user and assumes total exclusive access to local files.
|