There was no way of knowing it was abandoned. I am taking a guess at the length of time ago it happened; my guess is informed by lack of quality of service and public-facing updates. It's reasonable to assume that the API degraded in quality over time as fewer and fewer / maybe no people were working on it.
I think it happened around May/June/July ish of this year. I remember creating a free acct using the free tier API for a coding project I did for an interview around April. Shortly after they killed the free access and I guess now it is totally dead :(