Netflix runs one service with more than a hundred different catalogues. What you can watch depends on the country your connection comes from, because the studios still license films and series territory by territory, and a title that is on Netflix in Canada may be absent in Australia and sit behind a different streamer in the United Kingdom. The US catalogue is the largest, the Japanese one has the most anime, and the UK one carries British series that never reach the American library.
A VPN changes which catalogue you see by changing where your connection appears to come from. Connect to a server in the United States, open Netflix, and the US library loads under your normal account; there is no second subscription and no change to your plan.
Netflix does push back. It keeps lists of addresses that belong to datacenters and VPN providers, and when it recognises one it shows the message about an unblocker or proxy and refuses to play licensed titles. The address is what gets flagged, never the account, which is why the fix is simply to use a different server.
GhostShield covers the five catalogues people ask for most: the United States across four cities, the United Kingdom, Japan, Canada and Australia. Switching city inside the same country is usually enough when one address is flagged.