How long can I stay outside of Thailand on a NON-O multiple entry visa without losing it?

The NON-O multiple entry visa does not have a specific requirement on the number of days you must remain in or out of Thailand. However, the key point is that you must enter Thailand before the expiration date of your visa. If you want to extend the visa while in Thailand, you need to return by the expiration date; otherwise, you would lose the visa and have to reapply.