I’ve kept starters going for several months...I think I kept one going for over a year. I find it a bit too inconvenient eventually because I go through phases where I’ll not even be using it for long periods of time and having to feed it and keep the container clean, etc.
I’ve started my own starter and also purchased King Arthur’s and kept it going for months. King Arthur’s is a great one to start with. I think it’s like $8 or so and you can get a nice already developed depth of flavor right off the bat. That way, if you decide to stop feeding it, you know you can still get a new starter from King Arthur, in just a few days which they’ve kept going for well over a century.
The cultures are much more tolerant of neglect than is commonly realised. I often leave a glass jar with a couple of spoonsful at the back of the fridge for a month or more without attention. It looks pretty sad then, but after a day or two back at room temperature and a small feed, it always comes to life again.