WCF client lifetime for autocomplete textbox

I have winform app where i have autocomplete box filled from external web service. Its based on devexpress textedit which has nice feature to fire buffered onedit event (its not firing every time user enter character). What is best practice when creating wcf channel, should i do it gracefully and for every onedit event (still about 1s period) create new channel and close it or its better to use one channel for whole session (form lifetime)?