I'll readily admit that this may be a silly question but is the provision of live services dependent on whether or not a device continues to be supported and do they cease when TT decides to stop updates? I'm guessing that they are device rather than account linked and wondering if an unsupported model can continue to receive them?

A TomTom 'Live' model has a SIM card installed whereas non-live models don't...so if you don't have a 'Live' model, TomTom can't send it a text message with any updates