Like searching for and discarding duplicates, regular backups of your library should be made (and stored in a safe location). Unlike an active EndNote Library, a compressed backup can be stored on the Cloud. However, you should move these files back to a hard drive on your computer, before attempting to open them and extract the compressed contents within.

To create a compressed (backup) library:

1. From the File menu, select Compress Library (.enlx).
2. You will be asked whether you wish to create a backup of your entire library or just a group, and whether you wish to include file attachments or not. If you are creating a full backup, make sure to include a file attachment. 
3. Click Next and select the destination where you wish to save your compressed library.