Hello Jarek,
I have already answered you by email while i was in Paris, but i answer here to give the information for other users who could have the same question
So, the link to renew or upgrade to Unlimited for already Pro users could be found directly in the subscriptions page on the pro website :
pro.joomlic.com/en/pro-account/account/subscriptions
Pro Users just need to login with their Pro Account to be able to renew, and at any time (you can access this page when logged-in even if subscription is already finished).
Best regards,
Cyril