WARNING!
You may only activate it only if you never had Play Station Plus before
A credit card is required to redeem your PlayStation Plus 30-day trial, but you will receive this trial without charge. Unless you cancel your subscription at least one day prior to the end of the 30-day trial, your trial will automatically convert to a 3-month PlayStation Plus subscription, and will automatically be deducted from your PlayStation wallet according to the PlayStation Network Terms of Service and User Agreement. This 3-month subscription will continue and automatically renew until you cancel it.
You may cancel your subscription via the account management on your PSN account or by contacting customer support.