When you sign up for a 'nickname subscription' you get a few perks, like extra sticker packs.
The sticker packs that come with your subscription are as follows....
Prime - Ghost
Prime includes all of the packs below too!
VIP - Caterpiller
VIP includes all packs below too!
Extreme - Koala
Extreme includes all packs below too!
Plus - Rabbit
Note: Plus is no longer available, but current subscribers with auto-renewing subscriptions can retain their Plus subscription unless or until they cancel their auto-renewal.
Please note that since these sticker packs are part of your subscription, they expire when your subscription ends.