However... the trial edition of Windowblinds lasts 30 days.
If you decide to continue on, you will have to purchase a subscription to Windowblinds or to ODNT.
If you don't, the theme you purchased won't apply (a theme/skin needs Windowblinds to apply it).
To download the purchased skin, go to: https://store.stardock.com/login.aspx?ReturnUrl=/myaccount/products
You should be able to download from there after logging in with the email you used in the purchase and your password. I suggest you keep your skins in a backup folder on your C: drive and on an external, back up drive.