Hello,
You might take an inpiration in the Content rating module that can be used to give live site users the possibility of rating any document on your website:
Content rating module overview.
The DocumentRatings column in the CMS_Documents stores the total number of ratings of the document. If you rate a document, the value stored in the DocumentRatings column is increased by 1.
The information whether the current user has rated a document is stored in a cookie called DocRated.
You can either use a cookie to store information whether the current user has clicked the Like button or use some custom table to store a relationship between a user and the documents that the user has checked so far.
As this is quite complicated feature, you can use the following page to suggest this features for one of the next version of Kentico CMS:
Kentico CMS suggestions.
Best regards,
Michal Legen