Regarding your question which has been locked,
No you do not have to keep this line active. Regardless what the CS rep replied, you can ALSO get data on that iPad by using your phone's hotspot to provide it. There is no reason to pay to keep that line active if you don't want to. This is just an added cost which MOST people don't really need since ALL Verizon plans except some grandfathered plans have a hotspot included. Personally, I would NEVER again purchase a tablet with cellular capability as my tablet rarely leaves my home or office where wifi is available and the rare instance it does leave, I use my phone's hotspot to provide data if I even would like to do so. I think you should save yourself ~$120/year and cancel that line of service and use your tablet as a wifi tablet.