A well known issue of the SQLExpress Edition of SQL Server is an issue with the Full RecoveryModel.
The problem is that the log is not cleared correctly as in the paid editions of SQL Server.
The Workarround for this is to perform a BACKUP LOG operation just after a BACKUP DATABASE operation.
If you don’t do this the transaction log may just grow forever.
How do I make SQLBackupAndFTP to perform this action?
It has to be just after the BACKUP DATABASE operation as any ongoing transactions between the 2 operations may interfere with the intention of this.