I am trying to make a number of pages on my WordPress website accessible only for ‘PRO’ users. The idea is that a registered user can become PRO by going to a certain page (or to his/her account page) and entering a unique code (/password). This would then make this user PRO, changing its user role in WordPress and giving him/her access to the ‘PRO-pages’.
It is not an option to password protect several pages in WordPress and letting users access these pages with a password, because I want to have multiple passwords.
Therefore I want this code (/password) to be unique. I only want to create several codes and want to share them with the right people, instead of having someone uploading the code on the internet allowing everyone reading that to update their account and accessing these pages.
Is there a way of doing this? Or should I go and ask somewhere else?