At the moment Tictail doesn't support subscriptions payments, unfortunately. Sorry about that!
There are a few stores we've seen use cool workarounds for selling subscription-based products.
Here's an example from Nordic Surfer Mag, which allows customers to purchase annual subscriptions for different prices, based on their locations: http://nordicsurfersmag.tictail.com/products/subscribtion
We've also seen magazines like Clash, from the UK, sell individual magazines each time a new issues comes out - it also serves as a great archive for back issues you might have in stock! http://clashmagazine.tictail.com/
Perhaps one of these workarounds will be useful for you? :)