Instances are processed by completing tasks. Some tasks are mandatory while others are optional. You can execute both optional and mandatory tasks from the Instance Details panel.
The task will be complete. If it was an optional task, it may still be available to execute (some optional tasks can be executed more than once). If it was a required task, the system may send the instance to the next task, removing it from your Work List. If all required tasks are complete, and ALBPM did not send the instance, then you have to send the instance manually.