When entering a license key in the Aligner License Server that allows for one concurrent user, the License Server will show "Single-User License" in the license type description of the license dialog.
Please note that you will have a concurrent license for one user, the type is just displayed incorrectly for one license. A concurrent license for one user will allow you to use CodonCode Aligner on multiple computers on an alternating basis (on one computer at a time).