NAPA is 3 years/36k mile warranties on most, if not all products sold.
With reasonable limitations... As long as you basically did not damage the part on install, mis-use or return with missing components. It will be replaced.
If replaced, the new part comes with its own 3 year/36k mile warranty on the same conditions. Get a receipt for the exchange to reset the clock... A lot of people don't bother. They walk in with bad part and out with new part, no receipt on the new one.
They keep online purchase history for a few years, but I keep receipts in with my owner's manual and take photos of receipts (backed up on Google Photos).
I rarely have had to return a defective part to NAPA in the first place, but have never had an issue with anything I had documentation on.