I played the free edition and got to level 20. I would like to continue playing my account with same heroes after I convert to a paid account. It is possible?
When you're ready to progress further, simply subscribe to access an ever-growing universe and continue leveling to 50.
Note that you can only play characters over level 20 if you have an active subscription. If your subscription ends or lapses, you would need to reactivate to continue playing as any character over level 20.