The subscriptions are usually for things like real-time traffic, traffic safety alerts, fuel prices, and updated maps. Sometimes they could be already included with your device, so check the box. I have a new map in mine, and there are subdivisions that aren’t listed either in it or Google maps yet, but that might be rare. FWIW, I have a TomTom One 30, which I think is probably the cheapest model out there, and the only think it doesn’t do is read aloud the name of the street; it just says “turn right in 200 yards,” “turn left now,” etc. Other than that, it’s perfect, and that’s not really a problem, but I’d get the read-street-name model next time. Also, the battery life sucks, and I like to use it while walking or hiking, but it dies too soon.