PDFlib Lite is available as open source. However, the PDFlib Lite license allows free use only under certain conditions. PDFlib Lite supports a subset of PDFlib's functionality; please see the PDFlib web site for details. The full version of PDFlib is available for download at » http://www.pdflib.com/products/pdflib-family/, but requires that you purchase a license for commercial use.
Issues with older versions of PDFlib
Any version of PHP 4 after March 9, 2000 does not support versions of PDFlib older than 3.0.
PDFlib 4.0 or greater is supported by PHP 4.3.0 and later.