Most places only care that you were a student with active edu. I graduated years ago and I still use the edu without problem. Most things say you need to be a student from university. Which I am/was. Very few places say actively enrolled student. It's a legal gray area in my opinion.

Many schools will give alumni edu addresses as well

Do you mean to technically get access, or to be legally allowed to use it ? Because for the latter, merely having a .edu isn't enough.

It's probably more complicated than that, because I assume there are places in the world where you can legally ignore someone trying to enforce such claim where they are outside of such jurisdiction.

I have a lifelong edu address but it's not what they mean of course. My reading is that you have to be an enrolled student or researcher.