You have to upgrade php within your host (or migate to another one). The hosting server is running with very old and obsolete php version 5.2.x… The recommended version is 5.6.x (the newest one is 7.0.x, but not recommended because is still incompatible with some plugins, some themes…). If you have to use the plugin “simple google calendar” your hosting server need to run at least on php 5.3.x…
