Hey there Maria,
Most shops will require a visual inspection before they will fill a completely empty tank, ie... 0 psi. They want to be sure the tank hasn’t been laying around collecting rust or contaminants inside it. As far as stale air goes, If your tanks are being used regularly and your fills are from a reputable shop, stale air is not going to be an issue. You can keep at least 500 psi in it and leave it in a cool dry storage area over the winter , bring it to your local shop in the spring, fill it and go diving. All these concerns are also why you have your tanks visually inspected yearly...
Todd (TColJeep)