Unfortunately we are unable to directly transfer subscriptions between HSReplay.net accounts.
As an alternative, we are able to merge multiple HSReplay.net accounts if they both belong to you, even if you use different Battle.net accounts. After merging, you will be able to login using either Battle.net account and switch between your battletags without logging out. You will have full Premium access and statistics for all Hearthstone battletags in your account.
Please get in touch with us if you wish to merge your accounts.