#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)\b(?:\d{4}[ -]?){3}(?=\d{4}\b)"
Local $sString = "Hi here is my card number its visa 4242 4242 4242 4242" & @CRLF & _
"Hi here is my card number its visa 4242424242424242" & @CRLF & _
"Hi here is my card number its visa 4242-4242-4242-4242"
Local $sSubst = "**** **** **** "
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