I've started betting more on the flop on these kinds of boards. Sometimes with top pair, sometimes with a flush draw or straight draw- really depends on the table. I'm probably overbetting this flop- maybe to 10 or 8. Your bet doesn't give him the proper pot odds to call, unless he thinks you'll pay off a flush with your stack. which I don't think is likely with just top pair. so- he should fold a draw.
Turn completes a weird straight. Bet is fine, again- if he's drawing he's getting the wrong pot odds. He might raise a made straight here probably not if he thinks you only have a king
River- I'm not always betting here when the board pairs. You should be ahead of a lot of stuff, but nothing that will call a bet. I don't even think queens or jacks would call another street. So I'm more inclined to check/fold to a bet of any good size.
As played, I fold. He could be bluffing with the ace of spades, but what Axs hands does he call these streets with? Just a spade draw- why not raise along the way? Maybe hands like A5, A3, 4-6spades, 7's, 5's,
This is pretty much the nuts when he does this, unless you have info otherwise. If I"m playing, it's a fold.