Within existing automations you can view the activity log in order to see who has been subscribed, unsubscribed or their latest action in the automation.
To do this select the automation from the Automations module. Then select Activity log in the top banner. Here you can scroll the list of automation activities or search a particular name to see just their interactions with the automation.
This activity log can also be filtered by the log or action to reduce your search.
The automation activity and subscription can also be seen on the lead details page. Search the lead name, select the lead and scroll to the bottom of the page to see the Automations widget. This will show all activity the lead has had with a Funnel automation.