All my RB433AH boards came with v3.25 ROS, level 5 upgradeable to v6 with 8 character lic key. After upgrade to v4.5, pressing 'update lic key' yields message:

failed: license key is up to date!

Does that mean the original key is good for 4.x and ROS will not expire in 72 hours?

yes, new devices come with new style key. you can tell by the number of characters in SoftID.

Old SoftID 1234-123
New SoftID 1234-1234

All my RB433AH boards came with v3.25 ROS, level 5 upgradeable to v6 with 8 character lic key.

Do you really have them displayed as upgrade'able to v6?

I am wondering because all the info about licensing I have read states that L5 license should allow you to upgrade to 2 next major versions and since now the stable version is 4.x I should be able to upgrade to v6.x.
In my case I have two Routerboard devices (rb450g and rb433ah) which were both bought this February and they both show me v5.x in "Upgradable to" info. They both have new license keys.

Best regards,
Piotr

regardless of what you see, you will be able to upgrade. I will check why you have it differently

regardless of what you see, you will be able to upgrade. I will check why you have it differently

Do you want me to send you the SoftIDs?