Only issue was I couldn't figure out any way to add more than two at a time to the CDKeys basket so had to buy four pairs and a single one. Redeeming them on the MS account and then converting to Ultimate went fine tho'.
I don’t think it does but I can’t say for certain. It might be that it becomes available again after a certain amount of time since you last redeemed it though.
I followed this a few weeks ago and it worked.
Only issue was I couldn't figure out any way to add more than two at a time to the CDKeys basket so had to buy four pairs and a single one. Redeeming them on the MS account and then converting to Ultimate went fine tho'.