If you want to know if a workflow is still running, you have different options. If you want to check the running state in your workscreen, simply call

boolean running = Workflow.isRunning(this, id);

The id is the object that was returned from:

Object id = Workflow.start(this, worfklowNameOrId);

On server-side, the call is different:

WorkflowAccess.getCurrentInstance().isWorkflowRunning(id);