In the early days of operating your new moped be sure to pedal like hell as Ben says, as required. You engine is still tight and forcing it do something like go up a hill at full throttle can seize your engine. Any time the motor seems to bog down, back off the throttle and pedal to help it along.
Eventually the engine will break in and it will probably do 30MPH, no problem.
with a single speed model, hils will always be a problem. That's why I like my Vespa Grande with its variator. That is what the Magnum uses.