Anagathics seem to be one of those game mechanics that are disruptive, and whose legality seems questionable.
Whether that has changed under Mongoose, seems a little unclear.
Doesn't seem something that Imperium institutions hand out as perquisites, and obtaining them seems something that characters have to do on their own.
I tend to view them like cocaine - anyone can obtain them, but usually it seems restricted to the higher tiers of society, and if you are a regular user, you'd want to be able to secure a reliable supply, that isn't too watered down.
This is pretty much how I thought of it since LBB days, but for my money, this actually has changed under Mongoose in a way that makes it interesting, has sound game mechanics and create wonderful possible conflict for the user. Here are my findings:
1) none of this works if you read the rules as meaning roll 10+ every term as opposed to Roll 10+ start on any term you want to begin. If you are a ref that requires it every term, then you might as well take a black marker to your book on the whole anagathic rules section and say your players are not allowed to use them period, that is the same as saying they must Roll SOC 10+ every term, pay Cr25K x 1D, oh but if they don't make the SOC 10+, at the beginning of the next term, they they have to age anyway, but now with all the money down the drain. It should be tough and costly, but not so tough and costly that you can never get the benefit from taking the tough and costly choice.
2) If you do this and are not a noble, the debt will set you up to be truly messed with by the referee once in game. I'd be thinking "Organ Repo" or something evil.
3) Even if you are a noble, it will like wipe out each of your 3 cash rolls and then some at a rate of one cash roll per term spent using anagathics. Better get that rank 5+ and have a gambling skill too. Do that and you might even muster with a little cash left in your pocket and no debt.
4) You are not going to see characters really go to 200+ years using this because the advancement roll limit will have you kick out of every career available except maybe drifter if the GM allows it. At most they might be able to squeeze off maybe 3-4 more terms using anagathics which creates so much medical cost/debt.
5)once they muster and start game, they have 30 days to locate and buy their next "hit". If it's me reffing, I'd say they already have a source from where they are from, but then every 30 days scratch Cr20K. They better hope for big scores, which is what I would want them to go for anyway. Remember there is a Cr10K limit on initial gear so no buying up extra doses... then maybe one day "ooops, I think I ran out man. Sorry! My cousin in the next SECTOR might have some..."
What's more, being noble and on anagathics can truly make you a target if your titles are inherited. Just ask the 3I Imperial family which is rife with anagathics.