If you absolutely cannot pay, do not steal. Instead, use WebPlotDigitizer (automeris.io). It is free, open-source, browser-based, and in many ways better than GetData for complex polar or ternary plots. You lose some desktop convenience but gain zero legal risk.
If the graph has a thick, noisy curve, don't rely on auto-tracing. Switch to manual point picking. Hold the "Ctrl" key while clicking to add points faster. The full license allows unlimited manual points. getdata graph digitizer 226 key better
Version 2.26’s automatic mode is its superpower. To get better, cleaner data: If you absolutely cannot pay, do not steal