At present, a British citizen who goes to live abroad can continue to vote for the next 15 years. (The Conservative Party 2015 general election manifesto promised to extend this to voting for life.) However you need to be on the electoral register.
Many Britons now live abroad, either because they are working or because they have retired overseas. Everyone knows about the retired Britons living in Spain, but there are growing numbers of retired Britons living in countries such as Pakistan, India and Bangladesh.
Even if you are living in the UK, you may well know Britons living overseas. For the good governance of our country, please encourage them to register to vote.
With modern technology, the process of registering is much simpler than it used to be.
Full details are set out on the Government website at this link.
The time to register is now, when people have plenty of time and no elections are looming. Advise your friends and family not to wait until just before election time.