method for creating a unique validation key/number
Well, you can always use a GUID. As you said it would be stored as a valid key.
I'm using django for a web-magazine with subscriber-content.  when a user purchases a subscription, the site will create a validation key, and send it to the user email address.
The validation key would be added to a list of "valid keys" until it is used.
What is the best method for creating a simple yet unique key?  Can someone suggest a standard python library for key-creation/validation/ect?
This might be a very simple question, but I'm very new. ;)