Are you looking for an older version of Paintshop Pro?
If you have previously purchased an older version of PSP, have the license code AND have registered it with your Corel account, you might be lucky: contact the Corel support and they might be able to get your a copy of that old version. It is not a certainty, but it is worth a try. Remember that you would still need to install any of the necessary patches. You can find them HERE for the versions up to X3, while the more recent versions have their patches on the Corel site.
If you need to purchase an older version, for any reason, you can often purchase them on Amazon. Don't try to get a pirated copy. You might cause issues to your computer or have other problems. Since older versions are generally inexpensive, don't take any chance.
Here are links to Amazon listings for those older versions of Paintshop Pro. They are affiliate links so if you purchase through those links, I get a small commission. Thank you.