Yes, I needed to switch to the free plan! However when I was logging into the dashboard, I wasn't receiving any notification that told me to do this, so it appeared as if it just stopped working.
I'd written support email as well and one of the team members had gone in and selected the plan for me - so when you went to look at it it was already working again.
I'm not sure why I wasn't seeing any alert notification to choose a plan after free trial to keep Algolia running.
When I installed Algolia for a client, I did see this, but not on my own account for some reason~ thanks!