Used my VPN to get on to the USA website site and there are no pop-ups or ads that mention anything about being free. (Clear out your browser history and cache to see if you still get the pop-up/ad)
May also be worth running Malwarebytes (Or similar) to see if there are any infections. (This applies to Mac, Windows & Linux as they are linked to the browser not the OS)

Bill
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English Riviera:
Live entertainment, Real Ale, Great Scenery, Great Beaches, why would anyone want to live anywhere else (I�m definitely staying put).