if you build a new system later and remove this one then yes a retail key with go across to the new system... you may have to ring Microsoft if this keeps swapping about within a short time but they will sort that out
all (
non-server12r2 data) retail keys are 'one key for one system'... real or inside vmware, Vbox or hyper-v does not matter.
however you can make working backups of that system as many times as you like and thats still considered one system for your retail key + you can move the system from one motherboard (real) or host system (
virtual) so for example;
- you have a v-box w8.1 with retail key and you purchase a new wx laptop to hold it next year... the vbox w8.1 is allowed to move across to this new wx laptop (host)
- or perhaps you want to try installing Adobe photoshop on it but don't want to risk everything... make a backup before installing Adobe then if the system blue screens you can still roll back to before the install. make another backup whenever you make a major change and then store all these backups on a nas so even if some crackhead steals your host laptop you can still recover the V system when you purchase a new host laptop.