though at the end of a clause

In the example, though and but is similar in meaning

I was tired.  I did not go to bed early though.

Tolley's answer was great, but I don't think it is correct to use 'however' as a conjunction as in that last example sentence - 'however' is a sentence adverb, not a conjunction:  Jane called Jack a bad name; however, I am not bothered, or Jane called Jack a bad name.  However, I am not bothered would be correct.

I am pasting in a handout I use whenever I get questions about 'though' as conjunction and adverb, based on something I found online several years ago.  It basically supplements what Tolley has said.

though as conjunction

We usually think of "though" as a conjunction as the more informal alternative of "although",
introducing a subordinate clause of contrast. When we use though or although, they introduce an
idea that makes the statement in the main clause seem surprising:

(Al)though I was late for the meeting, I decided to go nevertheless

(Al)though the sausages were past their sell-by date, I ate them and didn't become ill.

though as adverb

"Though" is used as an adverb with a meaning similar to "however". Again it indicates a contrast. Used in this way, it occupies either mid or end position in a sentence and makes the previous statement or idea seem less true or appealing:

I thought Steve's essay was very good. ~ Yes, he made some good points and it was good in parts.
It was a bit repetitive, though.

I drove that new convertible the other day. Very impressive. ~ Isn't it rather expensive, though?

It seems he's still suspected of the crime. His main defence, though, is that he spent the evening with his girlfriend and she seems totally credible.