You can enable Audit logs and it will logs chats into /openfire/logs/ (Server > Server Settings > Message Audit Policy). But these logs are in xml format, not read friendly. You can try using this app to view them Openfire Audit Log Reader
You can enable Audit logs and it will logs chats into /openfire/logs/ (Server > Server Settings > Message Audit Policy). But these logs are in xml format, not read friendly. You can try using this app to view them Openfire Audit Log Reader