They costs about Cr 700,000 each term!
How can anyone afford this from benefits (or be in great Medical Debt)? Or maybe it is a mistake in PDF?
It's not worth it at all. Also it requires a SOC10+ roll and player need to make two Survival roll instead of one.
Second, the drugs cost 1D × Cr200,000 for each term the Traveller uses the drugs. These costs are paid out of the Traveller’s eventual cash benefits. If the Traveller cannot pay these bills, they go into debt — see Medical Debt on page 49.
I found this in Drugs section (page 109 Core Book):
Anagathics (TL15): These slow the user’s ageing process. Synthetic anagathics become possible at TL15, but there are natural spices and other rare compounds that have comparable effects. Anagathics are illegal or heavily controlled on many worlds. One dose must be taken each month to maintain the anti-ageing effect. They cost Cr20000 per dose.
Here it costs only Cr 20,000, but per month it would be Cr 960,000 per term (4 years).