Let's say I have an activity (let's call this Activity A) that is scheduled to end at a future date (for this scenario let's have the scheduled future end date of 3/30/2019). A visitor visits the site 3/25/2019 and is placed into Activity A test experience. If the same visitor visits the site on 4/1/2019, will the visitor still be cookied in the experience they saw on 3/25/2019?
Not sure if this is the question that you are asking but the activity will deactivate after the set time. This prevents new and returning visitors from getting whatever experience is behind the activity.