curl --request GET \
  --url https://api.sprucecollective.co.uk/admin/subscription-tiers/{id} \
  --header 'Authorization: <api-key>'

{
  "active": true,
  "amount_cents": 123,
  "created_at": "<string>",
  "currency": "<string>",
  "description": "<string>",
  "display_name": "<string>",
  "entry_credits_per_period": 123,
  "features": [
    "<string>"
  ],
  "id": "<string>",
  "image_url": "<string>",
  "name": "<string>",
  "site_id": "<string>",
  "sort_order": 123,
  "updated_at": "<string>"
}