License upgrade to higher tier

Hi, I’d like to upgrade my license to a higher tier, can someone point me to the correct procedure for doing that?

If you have a Free license, you can’t upgrade it.

You can purchase or upgrade Pro licenses here.

If you already have a Pro license and want to use it with more devices, you can purchase additions here. Just enter your license key, and choose how many devices you want to add.

Thank you for reply!
I did purchased 2 more seats but trying to activate my same license code to the second seat it says it is not eligible for version 9, but original license is lifetime updates.
License purchase told that new seats inherit all from original license.

Did I missed something ?

Please contact me directly on [email protected] with the license details and I will have a look.

Thank you for help!

Does this mean if I bought Pro, I would only be able to use the free version on my laptop, and the Pro on my PC, even though they’re using the exact same /appdata/ with the exact same IMAP email addresses? or?