I stumbled upon this while signing up a friend to Topcashback to get a VPN. Was looking at getting him Surfshark, but 100% cashback on a well established no-logs VPN is a no-brainer.
I have no idea how many years you can sign up for with it or if they are stackable, but at a guess, at least 2 years + 2 months. Which is normally €51.74. You also have the option to sign up for their antivirus for €1.45 per month and a dedicated IP for €4 per month.
I have just signed up. I can't see why I couldn't do it again and again etc..
REVIEWS HERE