yup, that's exactly why software is so valuable. write once, sell infinite.
the challenge with a lot of software businesses is that there's still a cost to sell the software. you need to own a channel to the customer (sales people, email distribution list, brand awareness, etc.). So while the software could be sold infinite times you still have to find/convince customers to buy it.
fortunately @k00b doesn't really have much cost of sales since we're just a community creating together so it can grow organically. So something he built 2 years ago can still run and continue to serve us indefinitely.