Florida usury laws are going to be inapplicaple because Florida has actual payday lending legislation, which will take precedence. With that said the payday lenders you have worked with *should* be following Florida law.
“Dot Com repeatedly and consciously chose to process Pennsylvania residents' applications and to assign them passwords. Dot Com knew that the result of these contracts would be the transmission of electronic messages into Pennsylvania. The transmission of these files was entirely within its control. Dot Com cannot maintain that these contracts are "fortuitous" or "coincidental" within the meaning of World-Wide Volkswagen. When a defendant makes a conscious choice to conduct business with the residents of a forum state, "it has clear notice that it is subject to suit there." World-Wide Volkswagen, 444 U.S. at 297, 100 S.Ct. at 567. Dot Com was under no obligation to sell its services to Pennsylvania residents. It freely chose to do so, presumably in order to profit from those transactions. If a corporation determines that the risk of being subject to personal jurisdiction in a particular forum is too great, it can choose to sever its connection to the state. Id. If Dot Com had not wanted to be amenable to jurisdiction in Pennsylvania, the solution would have been simple--it could have chosen not to sell its services to Pennsylvania residents.” (W.D.Pa. 1997)
If you identify the name of your lender, and locate the state they are incorporated in, it is quite easy to check with the governing agency which requires licensing, to see if they are licensed. As an example, ameriloan is not licensed in Oklahoma, nor Nevada.