What happens to purchased copies of my book if I remove my book from the Apple Books store?

As per the subject line,I've had a book in the Apple Books store since 2017. Sales have been low and I was thinking of removing my book altogether. I'm not going to explain why since it's irrelevant to my question :)

I'm concerned about what would happen to the customers who had purchased my book in the past. Do their copies get automatically deleted or are they still available? I'm hoping my book would still be available to them since they paid for it. This is why I'm on the fence about deleting my book.