WP Sales Booster Allows user based timer , so you can set any special discount code or note with specific time frame for individual user and individual products . and can set the timer 0 to 120 minutes . After this time frame special coupon code or discount will be disappeared
Products> Edit Product> WP Sales Booster Pro > User Based Timer [You can Show Custom Discount Code And Note With Fixed Date Timer ]
Here is short video tutorial
