Dude, you need to know how many mg/mL the stuff in the vial is. You might also inquire a lab certificate of analysis, to confirm that's actually what's in the vial.
Multiply the mg/mL concentration by 10 (the number of mL's).
Divide by 500mg. That's how many weeks you get out of a vial. Write that number down.
Divide 10 weeks by that number I just had you write down. That's how many vials you will need. Geez.