Even after switching to a Regular Pass, you can still use the gifts you received from a Premium Pass.
You can enjoy the following perks with an active Premium Pass.
・ Unlimited viewing of sleep data records and statistics
・ Daily Bonus Biscuit upgraded to a Premium Bonus Biscuit
・ A bonus 100 sleep points each day that you track sleep
・ Access to the Premium Exchange for exchanging your sleep points
・ Monthly gifts of a Good Camp Ticket and 1,000 sleep points
・ Rewards every three months
・ Access to a diary where you can write notes about your sleep