Please let me know if you have an updated user guide. It appears the existing user guide has a broken link:
For more information about the API resources, refer to the following links from IBM: ILMT: https://www.ibm.com/support/knowledgecenter/SS8JFY_9.0.0/com.ibm.lmt.doc_9.0/ com.ibm.license.mgmt.doc/integration/c_rest_api_license.html
the IBM page returns with "Resource not found"
The requested resource is not found: /support/knowledgecenter/SS8JFY_9.0.0/com.ibm.lmt.doc_9.0/com.ibm.license.mgmt.doc/integration/c_rest_api_license.html
You may want to replace it with this link which does have some great information on the API calls to ILMT.
Please let me know if you have any questions.