In-ear plugs aren't likely to be forgotten, but they won't prevent your ears from equalizing, either. In fact, for years I flew airplanes that were loud enough that they required earplugs as well as a noise-attenuating headset.
For walking around the airport, you can put in earplugs, but bear in mind they don't necessarily protect you. Much of your hearing damage can come from vibrations entering in around the ears, not just through the ear canal. A headset ("ear defenders") takes care of this, providing protection and dampening where it's needed most, as well as preventing fatigue, pain, and damage through the ear canal.
An ear-protecting headset can be had for very little, and various models are available which fold up compactly and take up little room in one's flight bag or gear. I simply clip them over the back of the seat or hang them on an arm rest, and they're always handy for those times it's necessary to get out of the aircraft.
Protect your hearing. Once it's gone, you won't get it back. It goes in stages and in parts, losing some hearing in this frequency range, some in that...you likely won't even know you're lost the hearing ability until it's too late.