Yeah, this is great. Hard drive goes out. Replace hard drive. Install operating system. Find out you have to wait 4 days after sending an email to get Vegas Pro installed again.
Never had this issue with Adobe.
An extract from point 9 in https://www.vegascreativesoftware.info/us/forum/vegas-pro-faqs-and-troubleshooting-guides--104787/
In VEGAS Pro 14.0 or later, you can also choose Deactivate the Software on this PC from the Help menu This option can be used as often as you wish. An internet connection is required.
Older versions of Vegas Pro than 14.0 are licensed under a system (as previously used by Sony) which permits use on multiple computers by one user; after an unspecified number of installations on different or updated PCs you may need to contact support to reset your "installation count".
If you have Vegas Pro 14 or later, you probably don't need to put in a Support request unless you've gone to My Products under your MAGIX My Account and weren't successful in de-activating any current activations for your Vegas Pro version. Usually, de-activating via your My Account frees up the allowable activation slots which should allow you to activate Vegas Pro on your newly rebuilt computer. However, de-activation via My Account can only be done once per month.
If you have Vegas Pro 13 or earlier, then the 2nd paragraph may apply and a Support request may then have been needed.
Please note that this is a user forum and nobody on the forum can help you with MAGIX's registration system if that system needs to be reset for you.
1. Log into your account. https://www.magix.com/us/support/my-service-center/
2. Deactivate the dead computer.
3. Install VEGAS.
4. Register/activate the fixed computer.
That's it! No more difficult than activating or deactivating Creative Cloud apps.