Your license is due for renewal on May 31st, 2020. You MUST complete 20 CEUs before your renewal (within the 24 months between May 2018 and May 2020).
A new regulation: One (1) of the CEUs must be pertaining to sexual harassment prevention. For more information on this, please see this article: http://nursing.illinois.gov/PDF/2019-11_IDFPR_SexHarassPreventTraining_final.pdf
Free CEUs can be obtained through many online services. Medline University has a Sexual Harassment module available for free.
Here is the sign on page to Medline University, you have to set up an account.
Here is the actual site for the course: