All pages have their title displayed above their contents. On the tool bar there is a Control Panel icon. Clicking it will bring you back to Akeeba Backup's (the first page of the component, with all the buttons).
On pages where editing takes place (e.g. the Configuration page, the profiles editor, etc) instead of the Control Panel icon there is a Cancel icon which discards any changes made and returns you to the previous page. On those pages you will also find a Save & Close icon which saves settings and returns you to the previous page, as well as a Save icon which saves settings and returns you to the same editing page.
On the bottom of each page, just above the Joomla!™ footer, there is the license information. On the page of the Akeeba Backup Core editions there is also a donation link appearing on the right sidebar; if you feel that Akeeba Backup was useful for you do not hesitate to donate any amount you deem appropriate.