  Measurements of the temperature and angular dependencies of the upper
critical fields $H_{c2}$ of a stoichiometric single crystal LiFeAs in pulsed
magnetic fields up to 50 T were performed using a tunnel diode resonator. Full
$H^{\parallel c}_{c2}(T)$ and $H^{\bot c}_{c2}(T)$ curves with $H^{\parallel
c}_{c2}(0)=17 \pm 1$ T, $H^{\bot c}_{c2}(0)=26 \pm 1$ T, and the anisotropy
parameter ${\gamma_H}(T) \equiv H_{c2}^{\bot c}/H_{c2}^{\parallel c}$
decreasing from $\approx 2.5$ at $T_c$ to 1.5 at $T\ll T_c$ were observed. The
results for both orientations are in excellent agreement with a theory of
$H_{c2}$ for two-band $s^\pm$ pairing in the clean limit. We show that
$H^{\parallel c}_{c2}(T)$ is mostly limited by the orbital pairbreaking,
whereas the shape of $H^{\bot c}_{c2}(T)$ indicates strong paramagnetic Pauli
limiting and the inhomogeneous Fulde-Ferrel-Larkin-Ovchinnikov (FFLO)state
below $T_F \sim 5$ K.
