If you launch at one of the Anglesey council manned launch sites you will need to register your boat, its £15 per year if registered prior at the council offices or £20 at the launch site on the day. You will be required to present a valid insurance policy with £3M public liability in order to get the registration.
You will then be required to pay a launch fee of £16. or £160 seasonal, discounts of £40 are available if you have a qualifying boating certificate,
Of course if there's nobody there like before 8:30 am or after 5:00 pm it's free!!