AIX

Ah - better finders of things on the web.

What I would say when asked this on site:
a) talk to your seller for the fine print. That is his job to keep you informed. If you are a reseller - talk to your IBM Business Partner contact. It is his job to be sure you know where to find this information for customer support.

b) since you are talking Enterprise Edition - there are few (actually none) limitations I can think of. Were you talking about the Express Edition (and a bigger system) I would have you look at this link: IBM Power Systems Software - IBM License Metric Tool - although this tool may be useful in additional situations where license compliance is an issue.

c) as far as updates go - you need both a hardware support contract (as bakunin mentioned) for firmware updates and a software support contract for AIX (and the bundled software) updates.

d) While you are "asking" either your business partner (i.e., the seller) or IBM - I would also ask how you can verify your support contracts, how to get to Passport Advantage (to download your licensed/supported software).
And because I do not know - ask if you can still download the base software even after the support contract ends - or, is the license dependent on having an active support contract. (This last point is something I do not know - I try to never lose my install media to "not have" this concern.)

I understand everything now, and I would like to thanks everyone that contributed to this thread!!!