Setting the return window is really simple. If you would like to prevent return after 30 days of purchase then just set value as 30. If want every customer to request a return no matter when they ordered then just leave blank.
Please note that this time limit is from the moment of order, and normally the law dictate that it must be from the point of delivery. For this reason we recommend a buffer. For example if your return policy is 30 days then enter 36 day limit.