Got this paragraph from the Expiry Letter announcement dated 1/8/17
2. Sell all or a portion of your options The Options are listed (ASXRLO) and may be traded on the ASX. The last traded price for PRLOs was 0.3c on 31 July 2017. Your options will cease trading at close of trade on Thursday, 24 August 2017 (last day of quotation).