[Resolved] Can't update nor revalidate older WPML plugin after rebying WPML.

I am trying to update WPML plugins after I rebought it. I did purchase it some weeks ago but asked for a refund afterward because of changing to a multisite structure.
Due to many problems, I came back to a single multilingual site by reverting from a backup (with the help of a professional developer). So I rebought WPML earlier this week, but I can’t update. (The WPML that I installed earlier was still there, because it was in the backup.) So I downloaded the newest version of WPML but saw that the old one was still there. I deleted this but discovered that all the drafts of my posts had gone. So I reverted to the version of last Monday (Feb 11), just after the new purchase.
But I can’t choose "update": under WPML Media, WPML Multilingual CMS and WPML String Translation, there’s the following message: “You must have a valid subscription in order to get upgrades or support for this plugin. Purchase a subscription or enter an existing site key.” When I click the link, I’m redirected to the “Commercial” tab of the plugins with the following message:
“Subscription expired. You need to either purchase a new subscription or upgrade if available. Revalidate subscription
If you have already purchased or renewed your subscription and you can still see this message, please revalidate your subscription.”
Revalidate doesn’t help, so I’m stuck here.
Pre-sales support suggested to delete the site key and renew it, but this has no effect

Link to a page where the issue can be seen: site behind an under construction page.

I expected to see:

Instead, I got: