Nearly every patient with a diagnosis of COPD is prescribed an inhaler or two, and you are told to take them once or twice a day for the rest of your life. Each inhaler contains 1, 2, or 3 drugs: a LABA, a LAMA, an ICS. Each of these types of drugs has been proven to be at least somewhat more effective than inhaling salt water (a placebo inhaler). For what exactly are they effective?
If you have ever seen a doctor for a sudden worsening of your respiratory symptoms (cough, phlegm, or shortness of breath, usually caused by a respiratory virus), and she prescribed an antibiotic and/or prednisone for you to take for a couple of weeks, that's called a moderate exacerbation of your COPD (and/or asthma). All three of these drugs have been shown to reduce your risk of another exacerbation. This was shown in dozens of large studies. Perhaps that is why your doctor prescribed your inhaler. However, none of these studies found that the drug(s) prolonged life or reduced a rapid decline of lung function (aka disease progression). Only smoking cessation does that.
What your doctor did not tell you when she prescribed the inhaler is the number of patients with COPD who need to take the inhaler every day for a year to prevent an exacerbation. That's called the number needed to treat (NNT). That number is 10-20 patients with a history of a COPD exacerbation during the previous year. The NNT would be much higher if patients with mild COPD, an FEV1 above 60% predicted, or no history of an exacerbation were included. The average number of exacerbations in study participants taking the placebo inhaler was about one per year.
Maybe your doctor prescribed the inhaler in an attempt to reduce your shortness of breath when you go for a walk, which improves the quality of your life (aka QoL). The LAMAs and the LABAs do improve FEV1 by an average of 0.15 liters for their duration of action (6-24 hours). That 10% improvement in your lung function (if your FEV1 is about 1.5 lters or about half of predicted) can reduce your dyspnea on exertion (DOE), and thus improve your QoL (as measured by a standardized set of questions,the SGRQ).
DON'T change your medications based on my comments above. Talk with your doctor.