Peter Magic, founder of Janoshik, has a YT interview where they talk about this. He says they are good for years in the fridge and decades in the freezer. He tells a story where he forgot a box of peptide in his garage for 10 years and when he tested it, it has degraded only 4%.
When reconstituted, the only one I've heard of having a 30-day usage window is Mots-c. There is a study available with supporting data on the interwebs. Other peptides will last longer, but you need to check for cloudiness or precipitate as it gets older than 30-45 days. My first vial of Reta went 8 weeks with no issues.
