As @Dave Creamer of IDEAS says, if you still have the old Pantone libraries installed with another Adobe application or an older version, you can copy those libraries across and continue using them where they’re compatible.
The important limitation is that they’re legacy libraries. They haven’t been updated in years, so they won’t contain newer Pantone colours. Pantone itself says the old Adobe libraries are missing more than 800 PMS colours. So they can be perfectly useful for existing work and older Pantone references, but you could encounter a colour in a new project that simply isn’t there.
And just to clarify why they disappeared in the first place this wasn’t Adobe suddenly deciding that designers shouldn’t have Pantone libraries. Pantone and Adobe ended the old bundled-library arrangement and moved current Pantone access to Pantone Connect. Pantone describes it publicly as a joint decision because the bundled libraries had become outdated, while some have said at the time that Pantone wanted the libraries removed so it could charge customers directly.
Either way, the end result is the same what used to be bundled with Adobe applications was replaced by Pantone’s own subscription-based service.