These are designs used in the testing of OpenLane 2 or higher.
They are not meant to serve as a reference per se. Matter of fact is, some of them are pretty bad. But they do exercise crucial functionality in OpenLane.
Each design has its own license. You may check the source headers for the files for said license.
If a file lacks a license and/or something is unclear, feel free to file an issue in the OpenLane repository.