I would think that Liberty would be within their rights to refuse to refund some or all of the expected amount if the items returned were not as required under the agreement.
Whether or not they would, I don’t know. Stuff like keeping customer goodwill etc might play a part. The odd partial return, likely fine, blatantly returning orders to keep the freebie, refund adjusted accordingly - but really, that’s just a guess 🤷🏻♀️