There are two options for using BlastEm in a commercial project.

Commercial Use of BlastEm under GPLv3
BlastEm is licensed under GPLv3 which allows commercial use without payment, but comes with certain restrictions. This is the preferred option for licensing.

Proprietary Licensing
If the GPL is a problem for your use case, it's possible to pay for a proprietary license. Please e-mail me with the details of your project to get a quote.