Its not valid anymore: https://www.advancedcustomfields.com/blog/acf-5-0-release/
We are so excited to release version 5.0 that we’re also offering a HUGE 50% off discount on our PRO version!
Now thru September 30, 2018, ACF 5 PRO is available for half price using the coupon ACF50! It’s our way of saying “Thank You” for your continued support.