Try:
my_model.booster_.save_model('mode.txt')
#load from model:
bst = lgb.Booster(model_file="mode.txt")
Note: the API state that
bst = lgb.train(…)
bst.save_model('model.txt', num_iteration=bst.best_iteration)
Depending on the version, one of the above works. For generic, You can also use pickle or something similar to freeze your model.
import joblib
# save model
joblib.dump(my_model, 'lgb.pkl')
# load model
gbm_pickle = joblib.load('lgb.pkl')
Let me know if that helps