While there is not a formal page limit in Final Draft, Final Draft was designed for industry-standard feature film and TV scripts. Most feature films do not run longer than 140 pages, except in very rare cases, with half hour TV scripts running around 30 pages and hour long TV scripts running up to 60 pages long.
For the optimal performance of Final Draft, we recommend sticking to the above page counts. If your script is significantly longer and you experience any issues when using Final Draft, we would recommend splitting your script file into multiple documents, and then reassemble it once you have completed your script.