CAN I USE ACTIVE TIME BATTLE FOR MY COMMERCIAL GAME

As long as you don't call it "Active Time Battle" nor use graphics that are too similar to an ATB from any Square Enix game, you're fine. Just add something original to it to make it look/feel different than a SE ATB.

Tons of games feature a similar system but represent it in a different way:
Coding-wise, games like Grandia, Megaman Command Mission, Super Mario RPG and Shadow Hearts all use an ATB-like system. They just add waiting time or hide the gauges or whatever in order to make it look different than the original FF4 ATB.

Dragon Quest games, for instance, use another system: at the beginning of every turn, action order is randomly determined with some influence of the Agility stat. Before Square and Enix fused, the same system was the base for a Square game called Saga Frontier, so in truth every company uses ideas from all other companies.