Sony announced today the service end of the rental part for the PlayStation Now. After July 11, 2017 you can use only as a flat-rate service. The change going to affects all the PlayStation Now compatible devices such as the PlayStation 4, the PC users via the PlayStation Now for PC.
After April 11, 2017 you can’t buy the 90 days long rental service right just only 30 days, 7 days and the 4 days long only until May 11, 2017.
More details can be found in here: http://www.jp.playstation.com/info/support/sp-20170404-psnow.html