I guess it depends.
I'll answer this on the presumption that your invention is patentable. Note that not everything is, but deciding whether your particular invention is patentable is the job of a patent professional, or at least some more research than falls under the scope of this question. I'm also leaving out anything pertaining to Alice, and patentability of software in general. That's a pretty broad topic, and you'd likely be best to speak with a patent professional about that as well.
Another really important thing to think about is that the United States offers a one-year grace period on patenting something post-public-disclosure, but other countries don't. You say you developed this a year ago, so if it was actually 366 days ago that you launched, or if you're looking for a patent in a country other than the United States, you've already lost your rights to patent anything you announced or made publicly visible at that time. If you're constantly improving or bringing in new features, and those are what you want to patent, that's not an issue.
First off, when talking about software, you should ensure you understand the differences between copyrighting and patenting your application. Even that sentence simplifies the matter a bit more than I'd like for it to. I won't get into copyrights, but in essence, registering a copyright (and you don't, strictly speaking, need to register it) will protect you from people stealing your code verbatim. Legal practice is always more complicated than legal theory, but that's the fundamental conceit.
A patent offers you protection, and I imagine you know this, to stop others from performing your invention, as described in the patent's claims. That means you'll have control over the algorithm--or whatever it is you're looking to obtain a patent on. In a pure open-source project, that may or may not matter. Particularly if you're going for the MIT license, or something similar that offers other developers a lot of rights, having a patent will probably just cost you money and not gain you anything.
However, you mention commercializing the software. If you're doing that, it can be beneficial to own the rights to stop other people from swooping in and stealing your implementations to sell as their own.
Ultimately, I can't tell you whether a patent is the right way to go or not. It's a business decision. Look at what your invention is, decide whether it's patentable (probably by speaking to a professional to whom you can disclose it), look at how much you intend to make, or how much you'd lose from other people stealing your code, and decide whether the (very approximately) $20,000 a patent might cost over its lifetime would be the best way to spend that money.