EverStart battery replacement?

I used car about 6 months ago and the battery keeps dieing. I've taken out my aftermarket stereo and my phone charger and all that to see if it was draining the battery, but it died again last night so that wasn't the problem. The alrernater and battery were both replaced about a year ago so I didn't think that was the problem but now I'm pretty sure it's the battery. The battery is and EverStart Walmart battery and it says it had a 2 year warranty on it. But I don't have the receipt, and the previous owner bought it. Not me. But it has a date on it, and it's only been about a year since the date it says it was put in. So will they replace it if I bring it to the store? I have a 2002 Ford Focus ZTS with 150k on it.

I would ask Wally World before you take it out of the car. Go to the automotive service cntr.
A car battery loses 1% of it's power each day it is NOT driven. One percent does not sound like much. But two months or sixty days, you have lost 60% of your power. 90 days= 90%. You went 6 months. Put a "trickle charger" (Battery Tender) on your next battery. They are fool proof, will not overcharge. Put a reminder sign on your steering wheel that it is still plugged in under the hood.

Auto parts store will check it for free.