Reimplement non-expiring tokens

Take a look at IFTTT for example (https://ifttt.com/docs/api_reference#authentication-flow)

They require a non-expiring access token.
You recommend to set the expiring time to a really big number. Should I set it to 2,52288e+17 seconds? (which would be 8 billion years if I'm correct, which would be the time the sun explodes)

I'm confused why the behavior was changed in 3.0.0