Hoc Spatium Mercede
This is another fine mess you've gotten us into.
Important: Recording an altered phase commits him to keep the card active until he does that phase. Once he uses a card to record an altered phase, he cannot inactivate, sell or voluntarily abandon the card until he has completed the altered phase.
This is from the 3.1 ed. rules from the List of Treasures, section 2, Birdsong (page 109). It's not so much that there is a special rule for the RoJ, rather there is a general rule that requires you to keep the card that gives you an additional phase until you've completed the action for that phase.