Both Mimic Intro and Mimic Pro will prompt you to save any work that needs to be saved by displaying a save button. If you start creating content but click out of the editable content, a popup like the one below will warn you of this.
Mimic Social works on an autosave system. As long as you maintain a secure connection to the internet the duration of your session, the work will be there the next time you login.
Usually, content that is typed will display a save button. For example, content that is written on the landing pages or in an email campaign. However, if the simulation doesn't prompt you to save any work after you make a change then it is automatically saved and you can exit out of the simulation without any worries of losing your work.