Yes, you definitely can use GPL licensed software in a commercial application (assuming you abide by the terms of the GPL license). The GNU General Public License (GPL) is a license created to ensure software freedom. In short, the GPL gives users the right to access, study, modify, and redistribute the source code to the software the license applies to.
The GPL is a “copyleft” license, which means that modified versions of the software must also be distributed under the same license. This allows companies to create and/or modify a GPL-licensed software program and use it for a commercial application, as long as the companies abide by the GPL requirements (e.g. by making the source code available to everyone).
There are some important things to keep in mind when using GPL software in a commercial application. Firstly, all distributions of the software, modified or not, must be under the GPL license. This means that any modifications you make must be published under the GPL license and made available for others to use. Additionally, if you modify the software and distribute modified versions, any GPLed program linked with it must also be made available with full source code.
Finally, once a GPL program has been modified and released as part of a commercial application, the source code must be made available, free of charge, to anyone who asks.
For more information, it's recommended to visit the GNU Licenses page on their website at https://www.gnu.org/licenses/licenses.html.
