Apparently, you can sign up your authorized users and receive separate memberships with two free passes for each of them. (lazytravelers.net)
For instance, a temperature measurement for anti-lock brakes might have several separate membership functions defining particular temperature ranges needed to control the brakes properly. (en.wikipedia.org)
I «m for separating membership in Readium Foundation from commercial rights to Readium SDK and any other technologies. (readium.org)