new hd

had to put in a new hd yesterday and went to reinstall blue iris but it no longer accepts the registration number do I need to buy a new one

No, you will not need to purchase another licence as long as the key you purchase was 100% real. What you should have done was deactivated BI from your old HD. If you couldn't as it was corrupt then email support and they will free up the licence key for you.
 
No, you will not need to purchase another licence as long as the key you purchase was 100% real. What you should have done was deactivated BI from your old HD. If you couldn't as it was corrupt then email support and they will free up the licence key for you.
Thanks for the help I found out what the issue is but now my active support plan expired last month so I don't think they are going to help me with the issue of resetting the key.