You can choose for the SmartClient to save your login credentials indefinitely by checking the Remember Login Credentials box in the Login window.
As long as these values are stored, the SmartClient continues to log you in to NetSuite whenever you execute a command.
If this box is cleared, the SmartClient retains your credentials only until you exit the SmartClient by closing the workbook. The next time you run the application, you will need to log back in.
Note: Your NetSuite credentials are stored safely in your local Windows user account, in encrypted form. To delete the credentials stored by the SmartClient, simply clear the Remember Login Credentials box and log in.