I'm having a similar issue. I downloaded the trial, used it and then it expired. Now I've bought the product but I can't activate it because it still thinks I'm on the trial version and won't accept my serial number of the product I just purchased. The serial number never activates it, it just keeps popping up with the window that says "your trial has expired."
. . . . I downloaded the trial, . . . then it expired. . . .I've bought the product but I can't activate it because it still thinks I'm on the trial version and won't accept my serial number of the product I just purchased. The serial number never activates it, it just keeps popping up with the window that says "your trial has expired." . . . .
I do not use Sound Forge, however with other Magix products when you receive the email with the serial number there should also be a link to the program download.
With an expired trial version you have to un-install the trial and then install the version the download link provides.
After you uninstall the trial version, check any Sound Forge folders left behind in C:\Program Files (x86), C:\Program files or C:\Program Data and remove any files in them.