If it was a licensed version, you should have kept the downloaded install from the old machine. How to get it back now, I don't know. Note that version 10 is several years old itself and was released long before Windows 8 came out so it only supports through Windows 7 officially.
You may need to contact Mark (use his profile on this board) or use the PCStitch contact point to find out if there's a way to get the old versions back (with unlock codes) or if you can get a discounted price on the new version.
If it was a licensed version, you should have kept the downloaded install from the old machine. How to get it back now, I don't know. Note that version 10 is several years old itself and was released long before Windows 8 came out so it only supports through Windows 7 officially.
You may need to contact Mark (use his profile on this board) or use the PCStitch contact point to find out if there's a way to get the old versions back (with unlock codes) or if you can get a discounted price on the new version.