> What's in it for Oracle?

Customer acquisition, like all companies with a free tier. It lets people experiment with their products and see if it meets their needs. Maybe those experiments grow up to be real products and continue running where they are. Maybe that user becomes an advocate for that product to their employer.

Right now there is no date when this free offer will disappear. For 3 yr I m using it.

Also keep in mind there's a lot more talent available to work with AWS, GCP, and Azure.