Hi there,
Thanks for buying AutoCollage.
When you uninstall the product, we do not remove the registration. So when you re-installed AutoCollage it is still registered. To verify this, if you go to the Options, Registration tab, the text in there should contain a sentence "This installation of AutoCollage is registered." If this is not true, then please contact us on acfeed@microsoft.com and we can continue to help you with this issue.
Many thanks,
Chris.