Can you lose your company match 401k if you quit your job?

It is possible that you could. 401k's have what's called a vesting schedule. All that means is you have to wait a certain amount of time to actually own the employer's contribution. Some matches are yours from day one. Most plans aren't like that though, so I would read through the info on your own 401k plan to see when the money will actually be yours to keep.