Ability Photopaint can export its own images as PDF files just fine, you just have to use the default PDF export function in order to save .apx files as .pdf files. Probably very hard without the original software as not many (if any) programs support APX graphics. Maybe some viewers could be used with virtual PDF printer installed.
Convert Ability Photopaint image file to Adobe Portable document format.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert apx to pdf on Windows
A photo and graphics editor from Ability productivity suites
Convert from apx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.