I believe Autozone is the only retailer that still offers free lifetime pad replacement regardless of cause, including wear. Does anyone lifetime warranty rotors??
Last time I used AZ pads on my kid's beater, I purchased new pads, installed them, then returned the old ones for a refund. No receipts needed (but always helpful)IF it is entered in their computer system correctly.
If you have a second vehicle, you could plan the work to use it to return the old pads with no money exchanged.
IF the OP is talking about lifetime warrantees offered by places like MIDAS, I imagine they put low quality products on that wear out fast. You get free pads, but pay exhorbitant charges for labor (just like their muffler scam).