The current public DJ membership is All-Access: $9.99 per month or $89.99 per year. Both billing options include Dig, Selects, Charts, Search, Friday Drop, and unlimited downloads.
See the current pricing page for the public offer. If you already have a membership at a grandfathered price, check Settings → Billing for the amount and terms that apply to your account.
Payments are non-refundable under the current policy. Cancelling stops the next renewal; it does not refund the paid period already in progress. MP3 files already downloaded to your device remain there after your membership ends.