There is no catch. We believe a cleaning tool should earn your trust before asking for your money. The free version is intentionally complete so you can see exactly how RJL System Cleaner works, verify that it's safe, and decide for yourself whether the registered features are worth it.
We don't show fake warnings. We don't cripple the free version to pressure you into paying. We don't collect your data. If you find value in the premium features -- especially the duplicate file cleaner, which recovers 5-50 GB on most PCs -- registration is there when you're ready.