3rd party application code
Multiple 3rd party software packages may be available under the "<LPCOPEN_PATH>\software" directory, such as LWIP, emWin, SWIM, FreeRTOS, etc. Whenever possible, the structure of the original package is maintained. A readme file included in the directory details the licensing, version, and original download information for the package.

NXP drivers for 3rd party applications
In some cases, NXP supplied drivers for support of 3rd party applications are also stored with the 3rd party code. Examples of these drivers include the LWIP EMAC drivers or the LPC43x0 M0 Core FreeRTOS tick driver.

Because 3rd party code structure is not altered, the include paths needed for using 3rd party code may vary.
Example:
To use LWIP, you would need to include (minimum) the following directories:
"<LPCOPEN_PATH>\software\lwip\lpclwip\arch"
"<LPCOPEN_PATH>\software\lwip\lwip\src\include\lwip"
"<LPCOPEN_PATH>\software\lwip\lwip\src\include\ipv4"
However, if you use a LWIP example that uses an RTOS, you will also need the 'netif' path
"<LPCOPEN_PATH>\software\lwip\lwip\src\include\netif"