Where i am assuming you are interested in the NowTV TV service rather than the NowTV Broadband & Telephone service ?
With the NowTV TV service you need to purchase TV passes, where there are five different categories which are cinema, entertainment, sports, kids or hayu.
You can pick and mix any pass you wish where there is no contract.
If you buy a monthly pass and in the future don't want to continue with the service it is important that you cancel any passes to avoid them auto renewing every month.
You need to create a NowTV account (including adding your bank card details) and need a NowTV supported playback device which has the NowTV App together with an internet connection speed of more than 2.5Mbps to watch NowTV.
If you are a new customer you may be eligible to a discounted offer (depending on what offers are available at the date of sign up or free 7 day trial depending on what pass type).
For further information have a read of this help article linked below which gives you a general outline what is NowTV.