Ah, I have a story about this!
Some years ago, I had a similar friend: yes, I had a bit more disposable income at the time, but I certainly wasn't in Lady Bountiful territory.
After endlessly picking up the tab (I know, I shouldn't have started in the first place), I decided enough was enough.
We went out for dinner one night and eventually asked for the bill, as you do.
Friend obviously expected muggins here to do the usual and pick it up, but I didn't.
And didn't. And didn't.
The better part of an hour passed, and eventually tight friend said, 'Ooh, we haven't paid the bill yet, have we?".
I replied, "No, you're right, we haven't. I got the last few times, I think it's your turn?".
They grudgingly pulled out their wallet and settled.
(Now, I should add that I did have the means to pay on me, because I was quite prepared for them to pull out an excuse and I wouldn't see a business out of pocket. I also found our waiter as we were leaving and gave them a VERY large tip to thank them for their patience.)
I do still see this person socially, because for all their parsimony they are actually quite good fun, but I don't do anything with them that costs money anymore.
It was a bit of a high risk gamble, but it paid off.