How to keep at&t from locking out my cellphone before I skip the country and stop paying my bills?

Is there something I can do while the phone is still unlocked to at&t so that I can still use it in another country. It's a Samsung galaxy s8

Read more: https://samsungus.org/qa/s8/how-to-keep-at-t-from-locking-out-my-cellphone-before-i.html