As usual, Cody is correct.  ServiceNow SAM populates lifecycle data from our library into the Software Model Lifecycles related list found on a Software Model record.  The data is related to the Discovery Map chosen.  If by chance we don't have data in our library, you can add it to the Software Model Lifecycles related list and it will be sent to ServiceNow for evaluation to be added to the content available to all customers, provided you've opted into the content service.

In short, if you want to track lifecycles for OS software, you do need to create a SW Model.  

Regards,

Daniel