This can be achieved with the Database Project feature. You can add the necessary documents in the project, save it and select ‘Load Last Opened Project’ under ‘Environment Settings’ in the ‘Environment → General’ branch of the ‘Options’ window. So, next time you open dbForge, your documents will be opened automatically.

Also, by default, the documents auto save feature is turned. Despite the fact that the documents may have not been saved yet, next time you start dbForge, all tabs will be restored. You can specify the file types to restore in the ‘Restorable file types’ section of the ‘Environment → Documents → Restore’ branch in the ‘Options’ widow. The restorable files with corresponding paths are specified in the *.xml file that is located in the following folder:
SystemDrive\Users\%UserName%\AppData\Roaming\Devart\dbForge Studio for MySQL\