The short answer is: listen to a subliminal audio once a day, at least.
If you mean to ask how many times should you listen to a subliminal to get results, then the answer is as many times as it takes. Forming a new mental pattern or mental habit can take between 21 to 66 days according to empirical research (more information here).
Different people require different lengths of time to experience change. For subliminal messages to work, your brain has to be exposed to the messages repeatedly. That said, listening to it many times a day for a short period of time isn’t effective; you need to listen consistently over a long period.
In other words, it’s better to listen to subliminals once a day, every day for three to nine weeks than listening to it multiple times a day for a week and then stopping. You may feel the urge to achieve your goals as soon as possible, but trying to accelerate them this way can actually slow you down.
Can I Listen to Two Subliminals at Once?
Other than not listening many times in a day, it’s recommended to listen to only one subliminal topic at any given time. You can certainly listen to multiple topics in the same day, but that can reduce the effect of the subliminal audio.
The reason is that focusing on one topic, such as increasing your wealth, requires resources in your mind. The more resources your mind can allocate on that topic, the higher the chance of you getting success.
If you listen to multiple topics at once, you have less resources for each topic. You can still achieve your goals, but it would most likely take a longer time than if you simply listened to one at a time.
The good news is you can listen to more than one subliminal audio a day if they are on the same topic. Again, using the example of improving your wealth, you can listen to several subliminals if they all are about that topic, using different affirmations or using different sounds.
Even so, listening to one or two subliminals a day on the same topic is enough. What’s important is to listen to them consistently, without missing a day if possible, until you start feeling the change.