I read some past discussions here that forbid f4 has 3 years shelf life. I purchased a small volume in 2016 but the bottle didn't say when was the expiration date. Should I dispose it in 2019? How should I dispose it? The bottle is small like an eye drop solution. Also, I have mite problem every September for 2 years. I want to make sure the forbid is still good this year in case I need it.

Thanks