No. And not because you're a crypto service. But because of this thing called General Data Protection Regulation (GDPR).

If even one of your ex clients comes from Europe, or you used any service based out of Europe, then you've to comply. It's non-negotiable.

Basically what it means is that you have to justify your need to collect (or in your case, retain) the data. You can't anymore since you don't have the business. Then, you need to get the consent (permission) of each user to take that data. You don't have it.

It's a bit more complicated than that, but that's the gist of it.