If you are referring to Lightroom v4.2 on a 'desktop' PC or Mac, then No. Your Catalog is not deleted and it resides in the Cloud with your photos for when you again [Sign In].
If you are referring to 'free' versions eg. Lightroom Apps on an iphone or Android device, then Yes! You could lose all your photos. It all depends IF you subscribe, and 'who' you subscribe with (Adobe or Apple).