the 600 calls in 5 mins limit is per API key.
we have a higher limit, that is per IP address.
the document API limit is part of the API key limit.
We allow multiple API keys of course, BUT please be aware of the Fair Use Policy. If we feel you are breaching it, we can and will deny you access to our services, without notice or reason and you will have to contact us to discuss future access.
If we feel you are not handling error codes properly (in particular 429) again, we will deny you access to our services, without notice or reason.