Gary,
For sure, support for Encore has been formally discontinued when PassportMusic stopped business, wasn’t that in 2020? And it was already extremely minimal when a so-called “Revived Passport” took over from GVOX in 2023.
The new Passport owner has never indicated he would support Encore5 – which I understand.
A few users here are trying to help other users in this forum, on a best effort basis, but we are unable to help on formal registration matters. It is probable that we are still bound by the license agreement we signed in the past, and that it would not be legal to publicly disclose registration keys here.
On Windows, the registration key is stored on the registry, at a well-defined place, and I guess that on Mac it should be similar. Recovering it may require some recovery copy of the registry.