Basically the way it goes is, if you want to use software on a new OS, to ensure it works as advertised, you have to upgrade, no matter the cost. Most makers have free updates (different word) to make them compatible with current OS, but if the software is that old and stated as Not-W8 compatible, then that is the answer.
Now you CAN try to use compatibility mode (yes it is that simple) that says it will run it like that version of Windows, but that is a last ditch effort, AND all features MAY STILL not work as advertised for many issues. Food for thought, if this is a XP programs most likely it won't work simply because since Vista a whole new security system for how the files are accessed, permission, account permissions and so on changed drastically that many programming techniques that 'cheated' to use 'core Windows code' without validating they were legitimate programs (basically how XP was having the Virus of the Day every day) was all patched up and the new requirements renders many old programs incompatible and required a complete REWRITE of code (UpGrade).