Been avoiding this thread all day because I know I get wound up by people having shocked reactions, but here we go (I can always hide it, I suppose!)
I fed DS1 until he naturally self weaned, he was about 4y3m when I realised he hadn't fed for a while. I had a ten year gap to the next child (because of new relationship) and DS1, then aged 12, asked me when babies usually stop breastfeeding - he had absolutely no memory of himself feeding until age 4.
Not that I think it would be harmful or weird to have a memory of it. But if you're worried - that's what happened with us.
I fed DS2 until he was 2.5, considered tandem feeding but in the end pregnancy aversion made it terrible so I kept cutting feeds short and he lost interest. DS3 stopped somewhere around age 3. I couldn't put an exact date on it, it was somewhere around last Autumn, but the thing is when they are that age, it's a bit like "when did you stop using a buggy" - there's a period of their life where it's an essential and you never go anywhere without it, and then as they get better at walking you find you leave it at home for some trips and then one day you just realise you haven't needed it for ages and you might as well pack it away.
Interestingly I had the younger two in Germany and I experienced far less negativity and weirdness around it. I found people, including some HCPs in the UK were quite frequently baffled at the concept of me breastfeeding at all (which might have been because I was a young mum) and especially so past 6 months. Then past 12 months it seemed like everyone was deeply uncomfortable with the whole thing, and there was a really awkward bit between 12-24 months where I felt like I didn't want to stop because it was working well for us at home and I knew that it was beneficial, but he had no sense of privacy or waiting until we got home and I found it very embarrassing when he would ask to feed in public. Post age 2, most people assumed that if he was ever breastfed it had stopped over a year ago and he only really fed at bedtime, so it stopped being an issue, unless I had to mention it for some reason and then people were usually very surprised. I was very grateful when a local branch of LLL opened up and I didn't feel like such an outlier! But I did have the oldest nursling there when it opened, aside from one of the leaders.
OTOH in Germany nobody cared about feeding in public even when they were older and when I mentioned it in an apologetic way (e.g. to nursery staff, paediatrician, colleagues explaining why I was tired) even when they were 2 or 3 I noticed that I didn't need the apologetic tone because nobody was surprised or shocked or thought it was a problem. They weren't even congratulatory which I did get a couple of times in the UK - it is just a normal unremarkable thing here, which I like. The only one time I had a confused reaction was when I went for an eye test with a ~6mo DS3 in tow and the optician recommended I should wait to buy glasses until I had stopped breastfeeding because it can change your vision (and she's right, it has changed). She was a bit taken aback when I said - well I fed my other child for 2 years, so I will buy these glasses now and just change them later. But she wasn't scandalised by it, just slightly surprised as though it was a new idea.