"Unlike KDP Select, Oyster does not require exclusivity. It’s open to all Smashwords authors. A single Oyster user could conceivably read multiple books by the same Smashwords author in a single month, and the author will be paid for each book. Smashwords authors will earn their royalty whenever an Oyster subscriber reads more than a sample of their book.
Oyster’s subscription service will help our authors connect with a segment of the reading audience they’re not reaching anywhere else. Oyster will also give authors yet another reason to steer clear of exclusivity and embrace full distribution with Smashwords."