For security reasons, Accessy will prompt you for your PIN-code every now and then to make sure that "you are you". This is also a security measure in case you accidently lose your phone and you don't have any screen lock on.
Please note: You have a maximum of 3 tries to provide the correct PIN-code. If you provide the wrong PIN-code 3 times, you have to login again by entering your recovery code. If you're missing this code, you will have to reset your account.