This is similar to Windows licensing (https://en.wikipedia.org/wiki/Windows_10_editions#Comparison...), where "Windows 10 Home" allows you to use 128 GB of RAM, while the various "Pro" versions allows up to 2 TB, and "Enterprise" up to 6 TB.

The limits used to be lower - I seem to remember laughing out loud at a Stack Overflow podcast, where they talked about having to purchase a new Windows license to be able to expand the RAM of a server.