Overview
Limitations
Embed.ly is a paid service, though you can also use it freely but some limitations apply.
In free version, there is a 5000 embeds limit as well as 15 http requests per second.
This means once you post five thousand cards in period of 30 days, you will not be able to use the free service anymore.
Also, if you have more than 15 embeds on single page, there are high chances not all of them will be rendered.
For the full list of pricing and limitations please visit the official embed.ly pricing page.