Memo's database located in ~/.memo/db file is an SQLite3 database which can be opened and modified using sqlite command line application or any other SQLite management tool.
The structure of the Memo's database is following:
CREATE TABLE words ( id integer, word text, positive_answers integer DEFAULT 0, negative_answers integer DEFAULT 0, PRIMARY KEY (id), UNIQUE (word) ); CREATE TABLE translations ( id integer, word_id integer, translation_id integer, PRIMARY KEY (id) );