It is true that Lightroon CC continues to work without a membership but the Develop and Map modules are what quit functioning with no membership. The big one is the Develop module, because without it you can't edit or adjust colors in your photos. You can still buy Lightroom but the cost of the Photography Bundle rivals buying the latest version each year. If Lightroom 3 meets all of your requirements, then its a matter of comparing it to what you get with the latest version. Other than new features there are a lot of other improvements done for speed, compatibility, and reliability. This might be worth reviewing System requirements | Lightroom. Lightroom catalogs can typically be converted to work with newer versions but are not backwards compatible, so another consideration.
CS5 downloads can be found here: Download CS5 products
Once support has been added for your camera model it will continue to be supported in the future but if you buy a new camera you might have to update to a new version of software for support
Camera Raw plug-in | Supported cameras
Hope that helps,
Where did you read that you can continue using a rented Cloud program after you stop paying the rent?
Recent change in policy for Lightroom only. Some features remain usable. Others are disabled until membership is renewed.