#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)\bPlus\b(?![^>]*<\/h\d+>)"
Local $sString = "<h4 class="Somethingsomething" id="something">Plus plan</h4>The <b>Plus</b> plan starts at $14 per person per month and comes with everything from Basic."
Local $sSubst = "{{Provider_Link '$&', 33}}"
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