Right now, I'm considering Neo4j Aura for my startup. I'd like to better understand what "Pay-as-you-go" means in Aura Professional section of the following page Managed Graph Database Service Pricing | Neo4j Aura Pricing
How the price is formed, what exactly in Neo4j database is taken into account? I mean the database size or number of nodes/relationships/properties plus number of executed queries… etc. ?