If you sell digital products, e.g. downloadable publications, to customers who are located in the EU you might be required to register for VAT in those countries. However, soon this won’t be necessary if your sales in the EU aren’t significant.
From 1 January 2019 an annual €10,000 (HMRC will set a sterling equivalent) threshold will apply to the total value of digital sales to the EU. Where such sales are below the threshold, your business will only be subject to UK VAT rules. However, you can continue to follow current rules if you prefer.