Hi @ester.martinez,
We almost forgot to mention another possibility for you to get access to Katalon Studio Enterprise (and continue to use Custom Keywords) simply through your engagement on our forum.
For almost every of your interaction on our forum i.e. log in every day, creating a thread or replying to others. You would gain Kudos, which you can use to exchange for gifts from our team (that also include 3-6 months of KSE/KRE/TestCloud/TestOps usage).
Learn more by heading to the thread below 
We hope this helps 
Albert from Katalon Community team