It sounds like your PD12 may have been a freebie and therefore possibly a neutered version. Virtually all packaged versions of PD are a very limited version not for typical sale. Post a pic of the "About" screen from PD.
I'm sure you could upgrade, I've not done it though with one of those versions. The item to watch out for with upgrades is one often needs the previous version installed to apply the upgrade again, this can cause some issues when one may need to put your PD15 upgrade on a replacement computer.
If me, in this case, I'd buy the full version of the PD15 product that fits my needs.
Many run PD15 on WIN10 although there has been some issues with the latests release of WIN10.
http://forum.cyberlink.com/forum/posts/list/51995.page#272761
Jeff