Yes. Sign up for a free account to get 2000 requests per months for free (with a maximum of 2 concurrent connections).
Alternatively, you can use "test-api-key" API key. It's limited to 50 requests per day.
If you downgrade your plan, you'll stay on your current plan until the end of billing period. If you upgrade your plan, you'll be upgraded and charged immediately, the remaining unused calls from the old plan will be added to your new plan quota and expire after 1 month.