You're using an Oracle product ;-)

The "Always Free Tier" stuff will get shut down when the expanded free tier expires unless you have a credit card plugged in. You can turn it back on... They don't always take cards they should. So, navigating their always free tier is somewhat complicated.

Also, there is a LOT of resource congestion for the arm systems. Be prepared to try every day to fire up new instances for a couple of weeks until you can find free capacity.