In general - you will be charged a 3 Eur monthly fee (paid for the whole year in advance, as a 36 Eur annual fee). You will receive two notifications before the end of the free GSM service period (which is 2 months). When GSM service expires - you will be able to renew your account from the Monimoto app.
Currently, the payment functionality is not implemented in our app so you can continue to use it for free. Once it is ready - we will inform all users by push notifications, most likely in 2018 Q2.