This may happen when the software has a demo, but this is not 100% functional, so you have to acquire it to see if the complete release is suitable to you, and you ask then a refund within 14 days
In my case I acquired Riffer and only after acquiring it I realized it was unable to do what I wanted
So be careful: if you acquire the plugin directly from the developer, you have the right to return it within 14 days, whatever the reason, and receive a refund, but if you acquire the tool from a reseller like Plugin Boutique you keep that right only for a few motivated situations not mine clearly!
I asked them to change the plugin with another at least, but no reply so far