Welcome @Tracy_Romm, taking a look online, I found these references to Lab Central / Dynamic Marketing.
What is interesting is the last one is being hosted on the WeDeliver.Email platform (https://wedeliver.email/). Have you used any of these services before?
Zapier is using OAuth for Keap API Connection, in which you have to authorize the Connection. That has been around for years, and no longer uses the Legacy API Key.
Note, any software being listed in the Third Party Authorizations are safe from the sunsetting of the Legacy API Key.
As you have 7000+ API Calls, that means on a daily average of 233+ API Calls being used. Do you have Opt In / Subscriber Forms listed on your website?
Do you have any WordPress Plugins that are connected to Keap / Infusionsoft?
I have written a guide to help track down things which you can access below.