Software Product APIs

We are looking to license our software with expiration dates and the like,
and therefore, I have begun to look through the Software Product APIs
manual.  Talk about having a headache!  Can someone give me a brief
overview of what APIs I need to use and which I don't?

I am fairly sure I need to work with these APIs (but please correct me if
I'm wrong!):

Create Product Definition (ASZCRTPD) API
          (to create the *PRDDFN object that I must include with my
software)
Generate License Key (QLZAGENK) API
          (to generate the license keys that my customers need to know to
use/install the software)
Retrieve License Key Information (QLZARTVK) API
          (to retrieve license key information in the software to verify if
expiration date has passed)

Do I need to use the Package Product Option (QSZPKGPO) API to create my
software deliverable?  Or can I just use the normal deliverable creation I
have always used (save files to CD/Tape) and include the *PRDDFN object in
my deliverable?  What about National Language support?  How is this done?
Must I use the PTF APIs to issue fixes?

I realize I'm babbling here.  There are a load of APIs in this manual (more
than 25!), but I don't want to spend my whole (working) life to get all
this going.  I can (and already have) written code to generate my own keys
based on my own imagination.  But these APIs are certainly more foolproof
if I can understand them and justify the time.

Thanks for any assistance!  Bill

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