Booster Packs allow you to add more credits to your account when you’ve exhausted your credit allotment for the month, but still want to download more music. There is no need to wait for your membership’s balance to refresh, and each Booster Pack purchase is a one-time charge—making them a convenient way to supplement your monthly membership whenever you’d like. They’re valid for 90 days from the date of purchase. The full list of Booster Pack options is available here.