Agreed. I would definitely not pay for this on a monthly basis. That being said, if you stick to the free plan, it does just what you'd expect.
There's a free, yearly or monthly subscription. The subscriptions really just divide a bigger chunk of money into smaller very affordable bits.
If you need the basic, free bit, perfect. Otherwise the SaaS system is in place for us to deliver a sophisticated service at very little up front cost. If you keep using it you get the updates pushed right to your app. The license can be reused on new projects, too.