Serif PhotoPlus 6
The software is from 1999, and was released for free in 2005. As the activation servers don't work anymore, Serif has published an universal activation key in 2022, which is "881887". (In the registration dialog, click the link for problems with activation, then enter the unlock key.)
Download is available here: https://archive.org/details/serif-photo-plus-6
Download is available here: https://archive.org/details/serif-photo-plus-6
Comments
My experiments with Serif products are that depending on year/product - a product code during installation, and then at first use you are required to activate.