I generated and my accounts become premium. A must have feature implemented. But you have to give some discount for your uploaders when they upgrade their account via earned money.
Now Implement Multiple file select and delete option, An option Copy Link When we click Right mouse button on link. Extend login and logout timeout atleast for 6 hours.
Please do this for security reason. User Login And Password are same for FTP. You should allow to choose a different password for FTP because most of user use RDP and RDP service provider are now a days steal Uploaders account and password.