Hey! Glad you liked it! Thank you for taking the time to try it.
To save the highscore I used
PlayerPrefs.SetInt("highscore", highscore);
the first "highscore" is the name I used to save this pref, and the second is the actual value of the highscore (in this case is an int variable)
To get the highscore, i wrote in the start method;
PlayerPrefs.GetInt("highscore");
Hope this helps!