You can use screenshots from Sketch Engine, provided that they are labeled properly as being screenshots of Sketch Engine and on condition that they only serve the purpose of illustrating Sketch Engine functionalities or to support a research goal and the number of screenshots stays within reason. This means that including two or three screenshots of each functionality is fine. On the other hand, including word sketches of the top 100 most frequent nouns in English would be outside the illustrative use and a fee would have to be negotiated with us.
Please adapt the screenshot caption to include something like "...generated by the word sketch tool in Sketch Engine..."