Koh Lipe is a popular island already but it is booming as we speak. More and more people are finding out about this beautiful island and hence more and more people show up every year.
If you want to book any reservation for Koh Lipe make sure you do so far in advance (at least a month and a half) as there isn't much accommodation and everybody wants to come here.
If you plan on coming in peak season (November through February) be sure to book a few months in advance. If you just show up on this island and expect to find a decent room then you may be sleeping on the beach.