Memory devices, systems including memory devices, and methods of operating memory devices are described, in which security measures may be implemented to control access to a fuse array (or other secure features) of the memory devices based on a secure access key. In some cases, a customer may define and store a user-defined access key in the fuse array. In other cases, a manufacturer of the memory device may define a manufacturer-defined access key (e.g., an access key based on fuse identification (FID), a secret access key), where a host device coupled with the memory device may obtain the manufacturer-defined access key according to certain protocols. The memory device may compare an access key included in a command directed to the memory device with either the user-defined access key or the manufacturer-defined access key to determine whether to permit or prohibit execution of the command based on the comparison.