curl --request GET \
  --url https://{defaultHost}/v5/app/memberships/{id} \
  --header 'Authorization: Bearer <token>'

{
  "id": "<string>",
  "product_id": "<string>",
  "user_id": "<string>",
  "plan_id": "<string>",
  "page_id": "<string>",
  "created_at": 123,
  "expires_at": 123,
  "renewal_period_start": 123,
  "renewal_period_end": 123,
  "quantity": 123,
  "status": "trialing",
  "valid": true,
  "cancel_at_period_end": true,
  "license_key": "<string>",
  "metadata": {},
  "checkout_id": "<string>",
  "affiliate_username": "<string>",
  "manage_url": "<string>",
  "company_buyer_id": 123,
  "marketplace": true,
  "custom_field_responses": [
    {
      "id": "<string>",
      "created_at": 123,
      "updated_at": 123,
      "question": "<string>",
      "answer": "<string>"
    }
  ]
}