You'll always have unlimited access to download all paid projects sent for editing.
To retrieve your edits, go to the Projects page and find the specific project you're looking for. Click the three dots and then click Review edits. Your Lightroom catalog will automatically load when selecting the project.
If it has been moved from that location, click Browse to locate the relevant Lightroom catalog. As long as the catalog has the original photos sent for editing and the same folder structure, Imagen will have no problems downloading the edit.