License upgrade to 3.0: How long it will be valid?

Sorry, I still did not get the logic in the license system:

If I upgrade to 3.0, will there be updates until 4.0 (and including 4.0) available for me?

well my license lasted till 2.9 .
Got an upgrade for 3.0 …til 4.0 (including 4.0)
So yes