Complexity is a parameter that regulates the amount of times a window can be reopened on push subscription. For example, if you specified a difficulty level of 20, then the user will need to either subscribe or cancel the subscription 20 times for that subscription to be no longer viewable. By default, the difficulty level is set to 100. Set the difficulty level to 0 for unlimited amounts of reopening a window or change the number to “1” if you want your visitors to see the pop-up banner only once. You can change this number at any time.