Readmill team has announced that in six days from now they will be fully closing down. All user data stored on their servers will be deleted so the current users should backup and export their data.
You should backup your Readmill data so that you can choose to move to another service if you want to in future.
1. While there is no easy way to export your entire Readmill history to be imported on another service, you certainly can export a reading journal that summarizes the time you spent in Readmill.
2. There is also an option that allows you to export the review and reading history.
3. To export any ebooks that you uploaded to Readmill, go to to the export page and scroll down. There you will find an option to download your entire library as zip file.
4. If DRM is involved you will have scroll down some more to find the instructions to transfer DRM licenses.