Changing USB device name

I have USB stick mounted by the command:

mount -o rw,users,umask=000,exec /dev/sda1 /mnt/usb

The stick have to be permanently mounted for backup purposes. Unfortunately ones in several days the device name “/dev/sda1” has been changed by the system for example from “/dev/sda1” to “dev/sdc1” and for this reason the stick must be remounted manually with correct name. Why? Is there any way to prohibit the system from device renaming?

Just mount it by uuid:

ls -l /dev/disk/by-uuid
sudo blkid