Yea its still good depending on where it was kept, temperature, and light. It's probably a bit less potent but even 10% less potent would be a lot for that.
yea it should be good.. cirius is right tho, it may have lost some potency depending on a few things... and yea, fentanyl is light sensitive, meaning light can damage it, making it less potent... but sometimes i will chew a piece of a mylan patch.. catch a buzz and stop chewing.... then put it away and forget about it.. (usually stored on my nightstand thing.. or in a cabenet) then ill find it and chew it, and it still delivers a decent buzz..