If you want to always have the number row on your keyboard, all you need to do it set it up once! This is how:
Open the Fleksy app
Tap Extensions at the top.
Choose the Number Row Extension and drag it to one of the spots at the top.
If the top spots are all filled in, select one Extension and move it down. Now you can drag and drop the Number Row to the top and voila! you'll be able to see it on your keyboard.