Upgrade 2 to 3 - does it cost

I have version 2.8.12, it suggests I upgrade to 3.nn.nn
Do I need to purchase another license key?

Sparkle 3 the application is a free update, in the sense that everything that’s in your 2.8 license still works in v3.

There are new features in Sparkle 3 that are not included, but you don’t need to purchase a different license key, you can go to the “Your License” window (in v3) and get the discounted pricing there.

This is 1) included for purchasers of a subscription and 2) entirely optional for who has a one time purchase license.