Tack lifters are sturdy little tools, so they should withstand a lot of wear and tear. They may, however, need a little care and attention to keep them in the best working order.
If you have been using your tack lifter to jimmy open paint cans, pry off skirting boards, and dig up large nails, then you may find that the head becomes dulled over time. By taking a metal file to the blade you can put some sharpness back into it, making it easier to pry up those tacks.
Likewise, because the staple remover type of tack lifter is often dug into furniture, the prongs may become dulled over time. To remedy this, simply take a metal file and sharpen them up.
As a general rule, store your tools in a safe place away from moisture to prevent corrosion and rust.