To see a list of all your purchases, and re-download the software, you can login to your PSEngine account at psengine.co.uk
Once logged in, you will see you can access Account | Purchases here
Under the list of your purchases, you can see View details and downloads.
On the details for the product will be any download links and license keys for your purchases or subscriptions.
Click on the version you require for your device to begin downloading.