Aging for 21 years

All great options listed above another option

De Molen Cease & Desist (non BA) is labled enjoy within 25years. You can probably buy a case and have 1 every year for the next 21 years

BA version I would think would not hold up as well

 

Hopefully the drinking age at that time will be lowered to 18, so you might want to reconsider your time frame.

 

I would age a few different styles that age well and not worry to much. I have heard chimay blue is great with extended aging, but haven't had it more than 3 years old myself so I can't vouch for it. Even if the beer is past it's prime it would be fun to open any 21 year old beer on your 21st.

 

About 2 years ago my daughter was born. During paid leave to be with the family, I brewed a huge barleywine.
Maxed all my equipment out on that brew.
It came out to about 12 gallons at around 12.5 abv.
I kegged most of it, but I wanted some bottles for long term aging.
I bottled a case of 12oz bottles and used champagne yeast for carbonation.
And to top it off I waxed the beers with pink wax(glue, crayons).
I'm confident that the beers will hold up for 21 years.
Tasting notes..
I killed a keg when it was fresh, it was a hoppy monster! It was pretty much all hops fresh..duh.
Had a taste of the second keg last year and hops have toned down but was still really hoppy.
Malts are started to shine more.
Opened a bottle a couple of months ago and it's coming along nicely.
I've have given out of some of my bottles and got nothing but great reviews.
Goin to save at least a 6 pack to share with my daughter.

In a couple of weeks my wife is having our second child. Another girl. So I'm thinking this go around I'll make a 15-16 abv Russian imperial stout this time.