Not all users are alike and some may have different needs than others. Allowing users to specify their security preferences will allow users to set the software-center behaviour to a password timeout value, entire session or for when software-center is open.
Solution #3 recommends we allow users to specify their policykit authentication preferences. The "Authorizations" utility in previous releases of Ubuntu used give the ability to do just this. It has not been maintained and apparently does not work with current versions of policykit.
No equivalent to polkit-gnome-authorization in policykit-1-gnome