Mailchimp Api 3

Mailchimp is retiring old api 1 and 2 June 5th.

Before June 5, you’ll need to ensure all integrations in your account use Mailchimp API 3.0. Below is the API key(s) used to connect to an affected integration. For security reasons, we can only provide the first 4 characters of your API key. 

Is there anything we need to do to keep our integration with them working?

This is the first I have hear of it. I will have to look into it, but doubt it will be updated before then.

Their pricing structure

https://mailchimp.com/pricing/marketing/?currency=...

has changed dramatically since this

https://www.picturespro.com/sytist-manual/articles...

was written.

Might be worth amending.