Actually I was reading the doc from wiki and MK says on license update:
In '/system license' menu router will indicate the time next-renewal-at when it will attempt to contact server located on licence.mikrotik.com. Communication attempts will be performed once an hour after the date on next-renewal-at and will not cease until the server responds with an error. If deadline-at date is reached without successfully contacting the account server, the router will consider that license has expired and will disallow further software updates. However, router will continue to work with the same license tier as before.
I was reading the entire page and my doubt was about that I purchased (and activated on the MK website) the license may be too early ?
I'm not sure whether the process was supposed to be "you buy the license after next renewal, but before deadline", but based on this note the CHR should try by itself (even though on mine, the credential are not saved anywhere, so I doubt it can login properly).
According to this info I should have time from next renewal up until deadline to hit the renew button from CHR and it should find the perpetual P1 license and be happy.
But as this is my first CHR install I wanted to be sure.