You've got a skybow Add-In (skybow action links, skybow list view search, skybow theme designer or skybow tabbed pages) installed on your site and you get the message "This app will stop working soon" then you don't have to worry about that.
This article will guide you how to get a working app again without loosing anything.
This is happening to you, because your are using an add-in that was installed from the office store (currently called AppSource). skybow decided not to offer them through this store anymore. Therefore you'll get the mesage "This add-in isn’t available" if you click on the "Find out why"-link.
No worries the add-ins are still available as a version you directly get from this portal.
But before you proceed to install it as described under point 4, please perform the following steps:
- Remove the corresponding skybow add-in (skybow action links, skybow list view search, skybow theme designer or skybow tabbed pages) from your site
- Delete the Add-In in the site collection recycle bin (second stage as well) if it is in there
- Remove the free license from your SharePoint Admin Center
- How to install and update a skybow SharePoint Add-In