How long can 50,000 last?
If you use 2,000 a month, it will only last 25 months. That is just about 2 years.
If you use 1,500 a month, then you'd be able to stretch it to 33 months. That's just under 3 years.
If you use 1,000 a month, then you'll have 50 months. Only 4 years and that time is almost up, isn't it?