#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(?<!^)\b[0-9]{5,9}:"
Local $sString = "13371337:Bat,TH,Li-Met,Blub,9.5V,370mAHr,1/2_AA-Cell,50pcs,13351234:Radio - Antenna 2.4 GHz AB/C midi (10p),15642345:Board SMB - Some Magic Board,95653345:Board SMK 6 - Some Magic Knobs - Mod6,56735632:Control Unit Z65 - Mod9"
Local $sSubst = "\n\g<0>"
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