PHPExcel - DEAD
PHPExcel last version, 1.8.1, was released in 2015. The project was officially deprecated in 2017 and permanently archived in 2019.
The project has not be maintained for years and must not be used anymore. All users must migrate to its direct successor PhpSpreadsheet, or another alternative.
License
PHPExcel is licensed under LGPL (GNU LESSER GENERAL PUBLIC LICENSE)