#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?i)(me)(?!([^<]+)?>)"
Local $sString = "I have ever been prone to seek adventure and to investigate and experiment where <span class='me'>wiser men</span> would have left well enough alone."
Local $sSubst = "<span class='highlight'>$1</span>"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm