All you need to do is post a tweet and you get a free three month subscription to Zenmate's premium VPN service. Been using their free version for a while and it's really good - the premium service gives you better speeds, access to premium servers from more countries and an option to automatically switch countries when you visit certain websites. All you need to do to start using it is install the browser extension, so you don't need to install any programs on your computer and no credit cards are needed to get the extended trial (normal trial length is seven days). There are Zenmate apps available too for mobile devices. The usual subscription price is £5 per month.

Also you can activate and stack multiple three month codes by using different email addresses if you want to. I got 12 months by using 4 different emails to generate 4 different codes. You need to clear cookies/use incognito before you use each new email