After the test has been started, and the real-time report is now available, you can copy and paste the Session ID into a document for later use (see below screenshot). This ID will be used as a parameter in the API to identify a specific session of your BlazeMeter test.

Currently, you can find the 'Session ID' in 2 ways in the JMeter test,

- In your Test report under the 'Original Test Configuration' report;

- During the 'Launch/Booting' page when starting your Test report.  

For the NTC (New Test Create) version, you will need, you can get the session ID from the following places:

-  In your Test report under the 'Logs' report. The Load Engines dropdown will include all the sessions for your test.

- During the 'Launch/Booting' page when starting your Test report.