Lightroom

Assuming you mean the cloud-based Lightroom for the desktop, if you terminate your subscription you will not be able to continue to use the Lightroom cloud apps. You will, however, be able to download all the images in the cloud to a local hard drive for subsequent use in a different editor.

If, however, you mean Lightroom Classic, you will still be able to use it....but in a special "reduced functionality" mode. Specifically, you would not have access to the Develop and Map modules, and you would not be able to sync to the cloud. All other modules and functions, however, would still be available.