NestPrint is a one-time purchase

There’s no recurring fee, and your license doesn’t expire. One license  covers 3 macs. 

Bug fixes and improvements within your current major version are free, delivered automatically through NestPrint’s built-in update checker. Major new versions with significant new features (such as a future v1.5 or v2) may be offered as a paid upgrade at a discounted price for existing customers and your existing version continues to work either way.