Don't worry - they haven't!
Most of the time if some analytics are missing from your dashboard, it's likely due to some of the filters cutting out the data. By default we only show the last 30 days of data.
To view and change the date filters, look in the top right corner of the dashboard. There you'll see a start and end date, defaulting to the last 30 days.
If you still are missing some analytics, please let us know! You can email email@example.com and we'll get back to you as soon as possible.