Nope, like Kaleb said, FL studio is a one-time fee, and doesn’t need to be paid monthly or yearly. You buy a license and voila – it unlocks life-time access to the program, as well as unlimited free updates. This is the same with FL studio plugins(specifically made by Image Line or stock plugins).
When asked “What are the best DAWs?” the answer is simple. Reaper is ranked 1st. FL Studio is ranked 3rd. People have several reasons to prefer Reaper over FL Studio. The most important reason for choosing Reaper is simple though. With Reaper you cannot only make your own themes, on top of that you can also configure the Reaper interface to best suit your personal needs. There are no limitations when it comes to customizing or programming Reaper.