  We investigated magnetic vortices in two stoichiometric LiFeAs samples by
means of scanning tunneling microscopy and spectroscopy. The vortices were
revealed by measuring the local electronic density of states (LDOS) at zero
bias conductance of samples in magnetic fields between 0.5 and 12 T. From
single vortex spectroscopy we extract the Ginzburg-Landau coherence length of
both samples as $4.4\pm0.5$ nm and $4.1\pm0.5$ nm, in accordance with previous
findings. However, in contrast to previous reports, our study reveals that the
reported hexagonal to square-like vortex lattice transition is absent up to 12
T both in field-cooling and zero-field-cooling processes. Remarkably, a highly
ordered zero field cooled hexagonal vortex lattice is observed up to 8 T. We
argue that several factors are likely to determine the structure of the vortex
lattice in LiFeAs such as (i) details of the cooling procedure (ii) sample
stoichiometry that alters the formation of nematic fluctuations, (iii) details
of the order parameter and (iv) magnetoelastic coupling.
