To ensure the ability to revert to an earlier version of your content you can use the revision option for a page. This is explained in more detail in the FAQ How do I use the page revision option?
Drupal Cloud sites are backed up nightly. If you want to restore your site to the state it was in on a previous day, send a request to firstname.lastname@example.org, giving the hostname of your site and the date of the backup you wish to restore. Backups are retained for two months.