Welding CO/Argon tank question

I bought my bottles. All that means is I own them if I never go back. Not rentals with a bill every month.
When I take them back they just exchange them like with a rental. They don't refill what I bring in.
Costs more up front but no monthly rent fees. Or an initial deposit.
Yup. My latest one, I own, but I exchanged another one I had that was dated good. All I paid for was the gas. As long as they're dated good and you exchange for the same size, all you pay for is gas.....least that's how it is here.