Policy without passing through Model

I've been learning about Policies and implementing them into my application. I understand I do can thing like

$user->can('update', $post);

But what if I didn't want to pass through a model. Say I'm trying to find out if a user is allowed to upload an WAV audio file. In my app it's based on the users package $user->package so all I would want to do is $user->can('uploadWav'); and then in the Policy check the $package.

If I do $user->can('uploadWav'); then I assume it doesn't know which policy to check?