Hello and welcome,
Here is a post that might help in general.
ML libraries usually let you “pickle” or save models to disk. Therefore you could save the model in an Anvil DataTable and read it into memory when you want to do predictions.
Unfortunately, I cannot see Keras on the list of libraries that are installed on Anvil servers (I believe that people on an Individual plan or higher can request libraries to be installed by contacting Anvil support).
Perhaps other people will have a direct solution but this is what comes to my mind.