You're in the original free Google Apps for Domains program, grandfathered. As the product has evolved, these grandfathered accounts have come along for the rid

You're in the original free Google Apps for Domains program, grandfathered. As the product has evolved, these grandfathered accounts have come along for the ride, at times with new G Suite features disabled behind a "try our paid plan for one month free" button. I don't know how many of these are left (I have one too), but they seem to occupy a weird product nether space that Google probably sees as a minor annoyance.