You will find your purchased pattern in your Pattern Library.
If you're a Seamwork member, simply login to your account and use the navigation to go to your Pattern Library. You'll be able to download your pattern from there. Once a pattern is in your pattern library it is yours to keep forever, and you can download it as many times as you'd like.
If you're not a Seamwork member, you'll go to www.seamwork.com and click Sign In, then click "Your Pattern Library."
New to working with digital patterns? Check out this helpful article.