It does seem you get the basic functionality, but to "unlock" everything, you would need to purchase an offline plan.
*Note that subscriptions created on your self-hosted server in this manner unlock server side premium features, but not client-side premium features (such as Super notes and Nested tags). To gain the full benefits of the Standard Notes ecosystem, you'll need to purchase an offline plan.
Offline plans offer you the full range of benefits of the Standard Notes ecosystem at a fraction of the cost of our hosted plans.*
Seems it's currently on sale 30% off; $39/yr or $113/5 yr