1. ANALYZE YOUR CURRENT FLYING STRATEGY. To determine whether or not you’ll get value out of a subscription, ask yourself how much you plan to fly during the subscription period and where you plan to go. By buying a subscription you are essentially tying yourself to a particular airline, so you need to find out how regularly it flies to and from your desired cities, and whether the seats you are paying for are actually available. If, for instance, most of your flights will be on regional jets that do not have seats with more legroom, there is no point in buying a package where those seats are your main draw.

And check fares on competing airlines. By buying a subscription you might save money on incidentals, but if the fares for the routes you fly are cheaper on other airlines, it simply doesn’t pay to commit to one brand. A good rule of thumb is that subscriptions are best for travelers who fly frequently, but not enough to reach elite status, which, in many instances, would allow you to get those perks at no extra cost. “If you’re flying a single airline 10,000 to 20,000 miles a year, then the subscriptions make good sense,” Mr. Leff said.

If you’re flying only two or three times a year, experts say, take a pass, because you may not fly the same airline each time. And even if you do, chances are you will not be doing so often enough to reap the benefits of a subscription, as opposed to simply buying the amenities you want à la carte.

2. CONSIDER SPENDING MONEY ON AN AIRLINE CREDIT CARD INSTEAD OF A SUBSCRIPTION. In general, the subscriptions “give people access to the kinds of stuff that airlines give at no cost to their bottom-tier frequent fliers,” Mr. Leff said.

So instead of buying a subscription, consider paying the annual fee for an airline co-branded credit card, which will duplicate a lot of the same benefits as a subscription. Many airline credit cards, for instance, give users priority boarding along with other perks like a free checked bag.