If purchased with the aids or in the trial, they can be returned during the full trial period. That’s 180 days at my Costco. I believe that can vary by country/state rules. I think the site says 90 days for other items except where noted.
From the site;
On Merchandise: We guarantee your satisfaction on every product we sell, and will refund your purchase price, with the following exceptions:
- Electronics: Costco will accept returns within 90 days (from the date the member received the merchandise) for Televisions, Tuner-Free Displays, Projectors, [Major Appliances](http://costco.custhelp.com/app/answers/detail/c/10/a_id/1213) (refrigerators above 10 cu. ft., freezers, ranges, cooktops, over-the-range microwaves, dishwashers, washers and dryers), Computers, Touchscreen Tablets, Cameras, Aerial Cameras (drones), Camcorders, MP3 players and Cellular Phones (return details will vary by carrier service contract).
- Diamonds: 1.00ct or larger: Members returning a diamond over 1.00ct must also present all original paperwork (IGI and/or GIA certificates) at which time they will receive a Jewelry Credit Memo. Within 48 hours, our Costco Graduate Gemologist will inspect for authenticity.
- Cigarettes and alcohol: Costco does not accept returns on cigarettes or alcohol where prohibited by law.
- Products with a limited useful life expectancy, such as tires and batteries, may be sold with a product-specific limited warranty.
- Special Order Kiosk and Custom Installed Programs: Custom product(s) manufactured to our member’s personal and unique specifications cannot be returned or refunded, except for warranty repair/replacement due to failure to meet specifications.
In fact, that’s even discretionary if there are exceptional circumstances.