I've never used GCP. Does anyone know at what granularity the Always Free service limits apply? Is it per Google account, per credit card, per billing name & ad

I've never used GCP. Does anyone know at what granularity the Always Free service limits apply? Is it per Google account, per credit card, per billing name & address, something else? Obviously they shouldn't be in the business of handing out unlimited f1-micros (etc), but I'm curious how you'd go about having more than one small project.