Read Only Access
Read only access will prevent files from being deleted from the USB drive, it can also prevent the files from being amended. It will not stop the file from being copied onto a computer though. Read only access to the drive also prevents other files from being written to the drive so it acts like a CD-ROM. If you still want the ability to write files to the drive then we can add a second partition to the drive for you.
Read only access to the drive prevents files form being deleted but it also prevents files from being added. To get around this you can partition the drive so any remaining space can be used as normal. So for example if you have a 2GB USB and a 1GB software program, you can partition the drive into 2 x 1GB. The section with the software is protected and the empty section can be used as normal.
When you insert the USB Drive into your USB port, 2 drive icons will appear: one is for the read-only partition and the other for the editable partition (user area).
Read Only Access and Disc Partitioning are very cost effective options if only looking to prevent content from being deleted. It will not stop the content from being copied though.