Well, though it's not highly essential, why can't I see subscriptions on the default registration page (mydomain.com/registration/), if I choose it here: http://d.pr/i/ZjJj
In curiosity, I tried to use all pages which BuddyPress uses. None of the pages work, except the activation page. Then I removed the default registration page from (mydomain.com/registration/) from BuddyPress and used it with Membership for registration. Now it shows the subscriptions.