How to keep muscle


Hi all, probably a stupid question but I've built lean muscle over a year of strength / and HIIT training 5 days a week. 2x Lower, 2x Upper and 1x core

If I drop to 3 workouts a week 1x Lower, 1x Upper and 1x core will I maintain the muscle I gained? I can't afford heavier weights so will be using what I have been. I just don't seem to have time to commit to 5 day a week workouts anymore, at least not every week, obviously if theres time I can squeeze extra workouts in. Please let me know your thoughts on this as a google search is contradicting. Many thanks