Some varieties are self fertile, LaVerne is hoping selling those types only. They die if it gets down to freezing. If you are in So Cal or So Fla you can put it in ground. They don't transplant well once they've gotten a few feet tall. It's not invasive, not really a tree actually most decline after two years and are replaced.

Papayas are male, female or hermaprodite. The hermaprodite are self-fertile and many grown from seed are taken from this sex. If it is either male or female, then you will need one of the other sex to produce fruit. You can tell by the shape of the flowers what sex it is (you'll have to look it up online.)