We use a lot of licenses and types of Virtualmin.
It would be convenient to enter the license number that you wish to renew or extend.
That is on Joe's todo list, he's been working on some modifications to the module that handles sales.
In the meantime, you have to use the slightly slower method of having Joe/Jamie manually renew your license.
First of all, we wish You a Happy New Year. :o)
Have You worked on the renewal process?
One more improvement could be to be notified when a licence is expired or will be expired in a couple of weeks.
since you are pro customer, it is probably better to create a ticket (aka "issue", this way you make sure that the virtualmin folks actually see your question)