REI membership is a lifetime membership so if you ever joined you are definitely still a member! I recommend starting here to see if you can find your member number. If that doesn't work you can call our Membership Services team at 1-800-426-4840 ext. 3906 or e-mail them at email@example.com. I hope this helps, thanks!
At REI, we believe a life outdoors is a life well lived.