Meaning of good in this sentences - good at the end of sentence

Yes, an informal intensifier. You can replace "good" with "hard".

The problem with this use of "good", aside from being an adjective and not an adverb (which would be "well"), is that you have to work out what good or well means in the context, which we don't have. "He let me have it" could mean he performed some act of violence on me, or he gave it to me, or he told me something, or whatever. "I hit the ground" could mean I landed after a parachute jump or I d

Okay, thank you for mentioning that problem.

But is there any basis for this use? i mean it does not make sense to use good as intensifier to me...

People say things like this. It's not the Queen's English, but it has meaning, if somewhat vague. I'm not convinced good is an intensifier as it describes how he hit the ground, etc. In "He let me have it real good", "real" would be the intensifier.

So its just replacing hard?

Yes I agree, not the queen's english.
But still it causes you to wonder why people invent such unnecessary stupid uses.

It's dated slang. You often see "but good"—"I let him have it, but good." Slang is supposed to annoy.

Never heard this use, even worse

"But good" is among the expressions listed under "good" in the American Heritage Dictionary. There is no such definition under the main entry.