How long can you stay on Flex Protex?

When you begin on a nutritional supplement, particularly one which is designed to help you with a particular ailment, how long can you take the product? I am going into my third month of taking Flex Protex for better joint relief. I have been surprising pleased with the results and am now worried that it might not be safe for me to continue long term. I am also concerned that its effects will fade in time and I will end up back on pain meds and anti-inflamitories. I would appreciate any help someone might be able to give me on how long I can stay on these. I am really hoping I can continue on Flex Protex and feel this good for a long time!