You can Add Association between your entity and System.session entity and according to usecase add association or remove association from session. you can retive your objects from session in microflow.
Sharma gives a correct answer but I want to add that associating entities to the Session is not really a best practice. All objects linked to the session are being kept around in memory for as long the session is alive and frequently send with the requests from the client to the server. The resulting hit to memory and performance can easily grow to be a problem.