If budget is your primary concern and you cannot afford a legal product key, consider legitimate free alternatives before resorting to piracy:

Entitles you to free technical assistance from the Golden Software team. Software Management:

As of this writing, a new Grapher license costs approximately $499–$699, though prices vary. Upgrades are cheaper.

For older physical copies, there is often a space provided on the Quick Start Guide to write down your product key for future reference. Activating Grapher 14

These tools cannot match Grapher’s ease of use for complex ternary or 3D surface plots, but for 80% of common scientific graphs, they are perfectly adequate—and completely free, with no product key needed.