you can download the free version and (usually) it will remember your license info.
Otherwise you simply have to activate it again, e.g. by clicking on the key on the title bar.
It'll ask for your license key (which, if lost, can be retrieved on this website, on the page where you can buy Bandicut).
Hope I was able to help you,
Thank you for reading my post. I hope you understand my "English".
I'm the German translator for some of Bandisoft's products and websites
(mostly Bandicut and Honeycam).