Has there been any thought to offering a lifetime or multi-year Premium membership program? I'd really like to upgrade to Premium, but I *hate* recurring yearly fees. Especially when it's a great service that I could see myself using for a while, I tend to want to pay for it once and get the recurring expense done with. I completely understand that a sustainable business model requires consistent revenue, and that lifetime subscriptions could undermine funding to enhance the service. Still, if the upfront cost is enough - it could make sense. Thanks!