When I started out with co2 I bought 2 Micromatics regulators
: it was 'cheap' for a brand new one, it was featured on one respected web site as the premium regulator for aquarium co2, I was afraid to buy something used, and it was shiny.
That purchase was a mistake, ~$140 down the drain. After 4 EOTDs, several middle-of-the-night emergency water changes, some dead fish, and countless hours trying to figure out what went wrong I finally replaced both with double-stages. Like every time I try to save $10 I waste a $100.
There are endless debates on 1-stage vs 2-stage, EOTDs, and so on and I don't want another one here, please. BUT this forum is where the information and expertise is - take your time, ask for help, and do it once and save yourself some headache and heartache later.
Given that you have already bought a regulator, do keep an eye on it and the fish once it starts to get empty until it earns your trust. I bet yours will work just fine for the next 40 years with 0 issues, but do prove it to yourself first.