When it comes to reflexive verbs, I always thought that they were only used with actions that make the subject an object, too. Anyway, there are some exceptions to that rule, e.g. se regaler or s'abonner.
While the former comes quite easy to me (the german form is quite similar) and might be related to a passive subject (the food or whatever is the subject in the sentence, but it's not acting actively) I do not understand the latter.
It's "Je m'abonne le chaîne de XY", but I am the subject of the sentence and the channel is the object. Hence there is neither an passive subject (I am doing something actively), nor is the subject identical to the object ("le chaîne" is clearly not identical to me).
I acknowledge that there might be more to reflexive verby than I know, but to me it just does not make sense in that case. Could anybody explain it to me?