All Switch owners across Europe can currently claim a free trial of Nintendo Switch Online, even if you’ve already made use of a similar trial in the past.
Copying a very similar offer currently taking place for those with US accounts, the free trial offer is available to claim between now and 9th January. To get yours, simply head to the My Nintendo website, log in with your account that’s tied to your Switch console, and activate the offer.
— Nintendo of Europe (@NintendoEurope) December 9, 2021
As a reminder, activating free trials of Switch Online will set you up for automatic paid renewals, charging you for a month’s subscription once the trial is over. To get out of this, head on over to your Account Information in the Nintendo eShop once your trial has started, and adjust your automatic renewal settings.