Access Premium group

Beschreibung: I managed premium access after user is registered properly (coming from Digistore oder integrated mediation) He arrives at https://wiki-to-yes.org/Benutzerhomepage. There the user will be identified and checked if he has an entry in the user database showing that he bought premium access. Then - if he is not in premium group already - he can opt access to premiumgroup via plugin subscribegroups, which will be offered in the pluginlist command. For some reasons user have problems to manage this plugin. I therefore want to offer a buttz0ons which is more clear. User clicks on it and he is in.
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