I have an old perpetual purchase of CS6. I still use Encore CS6 for DVD and Blu-rays that are sold by clients. Yesterday when I went to finish up a DVD for a client, it told me to enter my serial number. The only problem is that my serial number isn't working for some reason. I tried reinstalling -- same issue. I would chat with adobe support, but when I click the link, it just brings me back to the "here are some answers to common questions" page.
Side note: what are folks using for DVD + blu-ray in 2020? Need something with the full funcationality of Encore, and ideally some of the additional features that Apple DVD studio Pro had like scripting.