The X7.2 update does remove the previous 5 GB limit for file attachments in EndNote online. It is now unlimited file attachment storage (and no limit to the number of references you can store) in EndNote online for EndNote X7 and up users who have their EndNote online account linked to EndNote X8 software on their computer.
Attaching PDFs to references in EndNote Online
Managing PDFs (delete, sort by criteria, view available storage space)
Note: To check your available space, go to the Organize tab and click on Manage Attachments