The trial version of Lightroom mobile is avaiable for a specific number of days and once the full vesion features stop working.
You maintain complete ownership of your images at all times. However, if your subscription ends, you will no longer be able to view, edit, or sync your photos in Lightroom on mobile devices. With Lightroom on your iPad, iPad Pro, iPhone, Android device, or Chromebook, you can continue to view and edit your photos for free, but you will lose access to syncing capabilities across your devices. You can continue to view and edit your photos using Lightroom Classic desktop.