Here's something I didn't expect: it's genuinely hard to keep in stock. A few months in I went to re-order and it was sold out. I checked back, sold out again, and ended up going almost two weeks without it. After everything it had done for my gums, that was exactly the stretch I didn't want to be skipping.
So I switched to the subscription. Now it just arrives, I never run out, and I don't have to think about it. It works out to $0.99 a day, which honestly stopped feeling like a purchase and started feeling like part of my routine same as my morning coffee, except this one my gums actually notice.
My honest advice: start with the subscription from day one. Not because of the price, but because the results come from not stopping. At $0.99 a day I never have to count tubes, and I never have to gamble on it being in stock.