I am looking to share a confidential PDF document to a group of people, and I would like to block their access after a period of time. Does anyone know how to do that?
(I have access to an Adobe Pro license)
There's nothing in Acrobat Pro to do that. There are DRM solutions such as the one in Adobe Experience Manager which can control access. This needs a server to run it on; expect a 5 figure annual fee.
How secure do you need it to be? If anything beyond not secure at all, then DRM is the solution.
Otherwise you can use a script, but there are many ways around it, such as disabling JS, changing the computer date, opening the file in a non-compliant viewer that doesn't execute scripts, etc.