Clause 9.1.1 talks about monitoring and measurement, and in particular discusses the need for ensuring methods give valid results. If the method of monitoring and measurement is to use software, then this needs to be audited to ensure that it is giving valid results, and that the monitoring and measurement is maintained.
In addition, clause 188.8.131.52 discusses control of equipment, tools and software used to automate, control, monitor or measure production processes. This requirements discussed that these items need to be validated prior to release and maintained. This would also require auditing.