I can't speak for WA as I don't work for them, but I am sure that, as SecurityAssist is an extension and not a solution, it is eligible for a refund within 15 days if it doesn't meet your requirements.
there is an entry in the faq section here securityassist/
under the section 'do you offer a trial or demo'
Although not very obvious, php is alluded to for extensions on this page dreamweaver-extensions/