There needs to be more than one access key, dare I say "unlimited', create them as needed. (Though I'm sure 10-20 would be enough, that's a lot of integrations.)
On to my point/reasoning.
In the example on the blog example:
"You have created a membership site. When someone joins, you want your membership/ordering software to interact with arpReach to ..."
Ok, so that uses the one available access key.
What if I have a 3rd party tool that I want to grant access to? I can use the same key. Well, what if I want to discontinue the 3rd party service, they'd still know my (one and only) access key.
I'm sure the easy route is to shut it all down and regenerate a new key, but that'd mess with my "membership" software as in the above example.
This gets even more complicated, say I have:
1. My membership software (I host).
2. 3rd Party Service #1.
3. 3rd Party Service #2.
The 3rd parties are the issue, and the issue is is only having one (1) access key.