Every cleaner should know the answer to this or frankly not be in the business. The warranty is the warranty. Claims are denied constantly for failing to provide a receipt showing they have been professionally cleaned in the last 18 months. Most add that HWE is the preferred method. It's that simple.
I have seen dozens of denied claims in my area. No receipt. When I leave a receipt for a customer who is cleaning to maintain the warranty I write just "Carpet Cleaning" in the description. I peronally don't leave room descriptions. To my knowledge my receipt has been used twice in 4-5 years for a claim that's been filed. The carpet retailer/stores continue to tell me they just want a dated receipt that has the customers basic information.
I can't help but add comment about the polyester consumer nightmare that seems to be ongoing. 2 of my customers in the last year and a half have filed claims for premature wear in poly traffic lanes where the manufacturer sent an "inspector" to document the claim. On one of these he/she used a wimpy digital camera (with flash) to capture what was described as unremoved soil. Hence, no wear.
I went back and used a white towel test and a flood lamp directly over the carpet. No soil on the towel and the wear/destortion disappearing with the light. The customer hired another cleaner, no change. I don't know the outcome. The customer was ready to go to small claims court for $3,800
It's plain to me that carpet manufacturers are intent on denying claims. This inspector came from a county 2hrs away, bogus. I write "Carpet Cleaning" and a few words about HWE and
IICRC methods, bla bla. But in the end it's the customer who must stand up for themselves and hell yes the warranties are real and they claims will be denied.