I know what you are thinking, but no – you can only use it once. If you want to return the mattress at any time up to 365 days after purchase you can do so without quibble. You can receive a replacement mattress or have a full refund. Say you first purchased the Medium Firm IKEA Mattress then got a refund and decided to use that to buy the Firm version. You do not get another 365-day trial. Otherwise, you could use trial after trial and never actually pay for the mattress! The answer to your question is just once!