curl --request GET \
  --url https://api.sprucecollective.co.uk/rewards/loyalty \
  --header 'Authorization: <api-key>'

{
  "created_at": "<string>",
  "current_streak_months": 123,
  "last_billed_period": "<string>",
  "last_bonus_amount": 123,
  "last_bonus_period": "<string>",
  "lifetime_months": 123,
  "milestones_awarded": {},
  "next_bonus_amount": 123,
  "site_id": "<string>",
  "updated_at": "<string>",
  "user_id": "<string>"
}