Hello
Look like you at some time updated Pro version gallery with Free.
The screen shot which you show - from OrdaSoft
Joomla Gallery Free
But if You have Free Gallery - It not ask activation at all.
Also, last order which I see from you, from 17-Oct-2019 - this very old order. We have 1 year update and support license. so we can't send to you new version.
so there I see so ways:
1 - You send to our contact form
ordasoft.com/contact-us-form - your supper admin / ftp access - and detail description how reproduce error - and we will check more detail what exactly you have.
2 you install OLD Pro version Gallery which you have, But first - please backup your site. I not know which current Version Gallery and Joomla you have - and what may happen if you install old version of gallery
3 You buy New Version gallery - and install it
Regards
OrdaSoft team