Yes. The free tier gives you 50 requests per day with no signup or credit card. Just start calling the endpoint at aurumrates.com/api/v1/spot.
Yes. All subscriptions are month-to-month with no long-term commitment. Cancel anytime from your dashboard and your access continues until the end of the billing period.
You will receive a 429 HTTP response. The API includes X-RateLimit-Remaining headers so you can monitor your usage. Upgrade your plan at any time to increase your limit.