Thanks for your interest in CanvasJS. Surely we will assist you.
The chart might have disappeared due to some technical issues, most probably due to misconfiguration of chart options or a bug and not because of trial expiration.
The Trial expiration does not affect the rendering of the chart in any way.
Kindly check the chart options. In case if the issue still persists, please share a static file reproducing the issue to firstname.lastname@example.org so that we can look into it and help you out better.
For any license related query, you can contact us at email@example.com.