I just wanted to share an observation I just made. I had an old laptop that I've been using since the beta with a Digital Entitlement. In preparation to pass it on to a new owner I removed the 500GB hard drive and replaced it with a 40GB drive I had laying around. After a clean install from 1511-1 media it did not activate. I didn't have time to do a lot of experimenting so I just installed 7 and did an upgrade keeping nothing. Now it claims to have a Digital Entitlement again (but I'm not sure how good that is).
I have changed hard drives several times. Changing the hard drive does not break the digital entitlement activation for Windows. You may just have been activating when the activation server was not working or overloaded. Also you say Beta, you had to upgrade a legit system to get permanent entitlement activation.
changed three times my laptop hard disk in the last two months...windows 10 activated after clean installation
i write right now from one of my test computers I have here 4 hard drives with different ten pro installs, and in the past I had more hdd/ssd working here I use only one at time all installs are entitled and I gained only once. maybe you had the entitlement for a different version of ten. c
One thing I forgot to mention is although I've changed HDs on a number of PCs a number of times without issues, this time I did not log on with my MS account. Perhaps the DE without an MSA requires an exact match but with an MSA a close match is enough. I don't have a record of which drives I've used in which PCs so I can't test this theory until I get a new drive.
I've used a spare HDD for all my (and my friends) systems to get a HWID (and none of them uses online msft accounts), on my main system it's now the third drive (now a ssd) and the HWID is still valid