Yes, you can keep a Bestway trampoline out all year. All parts, including frame, springs, net and mat, are designed for longevity in all weather conditions. 

We do, however, recommend taking the trampoline down if it is not going to be used over winter or if there is going to be heavy winds or extreme weather conditions.

Please also note that during periods of heavy snowfall, if large amounts of snow build up on the jump mat, the weight could impact the integrity of the mat.