I left the UK around 14 years ago, my own personal "Brexit" if you will, making the most of freedom of movement within the EU to immerse myself in the Spanish culture, language and lifestyle. I haven't looked back and the shambles that is Brexit has only convinced me further that I made the right decision. My next step is applying for Spanish citizenship, given my desire to personally remain a part of the EU and my chosen country of residence, even if it means renouncing my British citizenship. Thankfully, I've lived, worked and contributed here for long enough to make the process relatively straightforward.
In the meantime, I'll enjoy my gaming here at GOG without any problems, although for the OP, there's no reason why Brexit should potentially have any affect on your purchases and ability to buy games here. The only thing that might be affected could be prices in the future, especially if the Pound tanks against the Euro and the Dollar, if regional pricing becomes a factor for a post-Brexit UK.
Nevertheless, I still hope that people back in the UK are somehow able to halt this entire mess, once and for all. Especially given the division and uncertainty it's caused for so many millions of people.