Hi,
I found [the document](https://cloud.google.com/free/docs/gcp-free-tier) explaining the free tier. Especially you might be interested in eligibility conditions:
-You have never been a paying customer of Google Cloud.
-You have never been a paying customer of Google Maps Platform or Firebase. If you have been a paying -customer of either of these services, contact support.
-You have not previously signed up for the free trial.
-You have enabled billing for your account through the Google Cloud Console.
-You aren't setting up a business account with a term sheet by working with a sales representative.
And the following exceptions:
-You can't have more than 8 cores (or virtual CPUs) running at the same time.
-You can't add GPUs to your VM instances.
-You can't request a quota increase. For an overview of Compute Engine quotas, see Resource quotas.
-You can't create VM instances that are based on Windows Server images.