Grommets on flip tops

Bare with me while I try to explain this.

I bought some flip top bottles from one site. With plans of putting mead in them. The other day I was surfing a different site and just out of curiosity I decided to see how much the flip top bottles were, and in small print it said they were only good for short term storage of brew.. So, now I’m worried that the grommets my not hold up to a year or longer storage. My mead is still fermenting so I have yet to bottle it, but does anyone know how long the seals will hold. If they won't hold up then ill just cap it in beer bottles.
I know the other day I opened a bottle of moonshine my dad made that was in a flip top… It was in storage for years, but the seal was still good. I guess I’m looking for a ballpark of how long it may last.

It will be a “sparkling” mead. I intend on taking the 6gallons and splitting it between two 3 gallon secondary fermenters. 1 will be mead, and the other will be metheglin which of course is mead with spices added.

I've had beer in 1L fliptops last for close to a year, no problems. Just make sure the grommet is in good shape.

Flip tops are great! I wish thats all I had...

I bottle most of my meads in fliptops. I've kept a sparkling mead for two years before running out a and never had a problem. I have some still meads that are 4 years old.

Not too long ago I found a few flip top bottles (Grolsch) that I made about 15 years ago. The beer was still carbonated and tasted ok.