I despise apps for this, apps for that....... Its a never ending screen of apps. If you don't buy a phone with huge internal memory, you eventually could run out I suppose.
Circle K has a program you can sign up for a discount, then you enter your phone number in the pump and it gives you a discount. My biggest gripe is the one Circle K close to home won't keep paper in the pump printers. Clerks look at you funny when you walk in to get a receipt.
My local Valero is real good about keeping paper in the printers. Once in a while I have to go in and get a receipt. The owner joked one time, "I let them run out so the customers have to come in and get the receipt. That way I get to MEET the customers

. He is a smart guy. Worked for Lehman Brothers in India until they went bankrupt, then he moved to the US and bought the gas station.
The Valero is only a couple of miles from the house. I buy a lot of gas there. They have non-ethanol gas and in the summer I buy about 20 gallons at a time. Its also a
Top Tier fuel. Before you poo-poo that,
watch THIS video.
I don't buy from Loves, Pilot/Flying J, all of their diesel is B20 which is a strong solvent. I learned to avoid it when I had the Sprinter MH. Mercedes says to avoid it, and if you have to use it, don't let it sit in the tank for long periods of time, and check the oil frequently because it can actually cause the oil level to rise as it contaminates it. (Thats what Benz says, not me). I top my diesel truck at the Valero, any time I'm heading out on a trip, he sells straight diesel. The local logging trucks and independent dump truck operators all buy from him.
Loves/Pilot/Flying J are always the most expensive at an interchange.
Charles