The QuickBooks Online Edition Login Key comes from Intuit by running the following URL:
https://login.quickbooks.com/j/qbn/sdkapp/sessionauth2?serviceid=2004&appid=71271511
and logging in. The “…” after Login Key: will launch a browser with the above URL. The connection string attribute for this item is IBizOELoginGUID. The default is an empty string. This value is only required if the QuickBooks Online Edition company file has user security activated. If you chose No security then leave this blank. This Key will expire after a period of non-use. If your application makes several connections each time you access QODBC you might want to return to this screen and press the "..." and login once, saving the new Login Key. Then you will not be prompted again until the non-use timeout expires.
Ask to login if invalid can be checked to allow the user to be sent to the Intuit WEB site to login if the Login Key is not valid. After the user has successfully logged in the user must copy the Login Key to the clipboard, close the browser and paste the Login Key into the Popup prompting for a Login Key. If not checked, and the Login Key is invalid, then an error message is returned to the calling program. The connection string attribute for this item is IBizOEPromptForLogin. The valid values are Yes and No. The default value is Yes. This is only useful if the QuickBooks Online Edition company file has user security activated.
See: How do I use QODBC with QuickBooks Online? for further details. | 
