#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)((?:[^.?!]+[.?!]\s+){3})"
Local $sString = "Some text goes here. The second sentence. The third one. And more. Even more. Still more. It's boring, but let's put some more sentences. Almost there. Ok, this is the last one. "
Local $sSubst = "\1\r"
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