GPS tracker for Android

I'd say yup.  From my 60 second look-see it says it sends your location data via the internet, so you will be using data.  How much and how often is another story.  

Yes, it does use your data plan, but it is very minimal.  For example if you use Runkeeper or something like that, you install the app locally on your phone via wifi, so that's all free.  Then when you're using it, the app just runs and pulls GPS data from the internal GPS on the phone.  It may download minor map location updates and such while you're riding/running, but the overall usage is extremely small and I'd guess in most instances almost zero.

When you finish your run/bike and save your workout it will upload the information to your account, but that is also a very small amount of information that will require very little data.

On most android devices you can see how much data each application is using, so if you're concerned you can watch it pretty close.  I think it will be negligible though.

In general, streaming music/video, facebook, and email are your biggest data hogs on a smart phone.  The misc. apps doing things here and there use very little data, generally speaking. 

*edit*

One more thing.  1400MB (or 1.4G) is a ton of data to use.  I am what I consider a power user of my phone and get hundreds of emails per day, stream music/video on occasion and am constantly on social media.  I typically use between 2G-3G total per month.  If you're only using GPS apps and little else I would guess you'll be under 10MB for the entire month.

I just looked at my phone and I've been using MapMyhRun and MyFitnessPal almost daily for the past 3 months and combined they're less than 10MB of total data usage.