meaning of "maintained their subliminal powers"

[KuaiLe]

I'm reading Emotional First Aid by Guy Winch. The author had a patient who was a self-help junkie with a penchant for positive affirmation programs and "he listened to countless subliminal messages, such as 'I am worthy and able,' which he assured me maintained their 'subliminal' powers despite the messages being listed in bold print on the packaging in which they arrived."

I'm confused about the meaning of this sentence. Is the author implying that even though those messages are clear to be seen on the product package, this patient still felt powerless after listening to them? If not, what is the meaning of this sentence?

[Tdol]

The patient felt that the messages were being conveyed at a subconscious level even though they were clearly displayed- a delusion on the patient's part.