Think of this example. I am a company ACME that is buying MS Exchange. I also bought a Server which we named ServerX.
Account - ACMEAsset - ServerX that I bought from you (we create a CI with this, called ServerX CI)Product Model - MS Exchange (this ...
Just want to note for anyone reading this after the fact, Anthony's answer is correct. You need to activate the plugin from the developer home as described above.