just a small and seemingly insignificant yet important point, there is no such thing as a US or FAA ATPL only ATP.
The FAA do not issue licences. They issue certificates.
In practical terms they are almost the same thing but certificates have a distinct advantage over licences, they never expire or need to be renewed. (only exception is the flight instructors certificate)
As long as you are current and your medical is current then all is well. If you stop flying for many years and want to start again all you have to do is get current again, no mandated further training or flight test or fee, just between you and your instructor as to whats required.