LPCXpresso IDE (Free Edition) is available for download and activation at no charge.
There is no evaluation version of LPCXpresso IDE (Pro Edition). However, the functionality for the Free Edition is identical to that of the Pro Edition, except for the download limit (of 256KB) and some restrictions related to SWO Trace. Thus, if you are considering purchasing LPCXpresso IDE (Pro Edition), you can simply use the Free Edition for your evaluation.
For more information on LPCXpresso IDE, including links to download, please visit the LPCXpresso main product page.