Make application still useful even when it is outdated

What will happen if one application becomes outdated? When we cannot update anymore due to lack of space or out of memory. For most people, the tendency is they will just leave the application on one side then try to look for something more efficient to use. My question is how can I make the application still useful when it is outdated? And how can I know if it’s time to update or when new version came up? I need some advices. Thanks.
