Did you know that you can manage your password and session expiration directly from your ShippyPro account?
To do that just access My Profile > Security page:
The first option will make your password expire every X days;
The second one will make your session expire, if you don't access any page in the meanwhile, every Y minutes.
If you wish to opt-out of one of those systems, you simply have to clear out all the fields and press Save.