I'm looking to transfer a CHR license as a birthday gift to a friend of mine. How do I do that?

Transferring licenses between accounts not possible. Maybe mikrotik staff help over support, don't know. Otherwise open a new account, buy a single license and give credentials to your friend for use.

https://mikrotik.com/client/transferprepaid

If you haven't already purchased it, you can use a reseller, and provide the reseller the account to apply it to.