That might be the case yes. I'm using the Home edition myself bought at 300$ years ago. When a new version is released I decide if the added functionality is worth it (difficult descision ).

A home edition upgrade is around 90 dollar. With Mathematica you can also use the Wolfram Alpha functionality. As an example when I go through the home work of my kids I often show how Wolfram solves the Integrals (through Mathematica). Without Mathematica this function is only available on-line with a paid Wolfram Alpha license. The WA Pro version is around 60$ per year.

The upgrades only comes when you have premium support as far as I'm aware. Without support You'll only get the version say 11.1.xx. So 11.2 is not a free upgrade. When you buy the professional version you have 1 year support included. As long as you pay the yearly fee you should receive the upgrades.