https://en.wikipedia.org/wiki/Portuguese_Armed_Forces
Portuguese Armed Forces:
"Active personnel 32,992 (88% males, 12% females) (2016)"
It is funny you bring this up. I was just commenting the other day that Portugal only has 33,000 soldiers so what is even the point of them being in NATO? What do they even contribute? They could not defend Lisbon with 33,000 much less provide allied support.
Now I know that some are actually deployed, doing a lousy job of guarding a base for us. #themoreyouknow
There are reasons. First, though they don't have a big military (in part because they're pretty poor for a Western European country), they're a pretty loyal ally. When we need them, they show up with what they do have.
Second, consider where they're located. Their mainland is at the western entrance to the Mediterranean. That's a big deal. In addition, though they've given up most of their overseas possessions, they've kept the Azores and Madeira, both of which have strategic importance.
Lajes Field is in the middle of the Atlantic, and it's basically a gas station for aircraft. With in-flight refueling, it's no where near as critical as it used to be. However, during times of war when it isn't practical to rely solely on in-flight refueling, it gets very busy and very important. If Portugal wasn't in NATO, we wouldn't have access to it, and worse yet, China likely would. Link.