“How many times can I use my creature’s ability? Just once?” I’ve heard that one a lot, especially among newer players; they want to know how many times they can activate a given ability per turn. The answer is pretty simple: As many times as you can pay for it! The vast majority of activated abilities have no limit attached to them, so the good times will keep rolling for as long as you can afford the price. You want to pump your Inferno Titan or your Dragon Hatchling twelve times? SO long as you’ve got twelve red mana for it, that’s totally legal! Do you want to activate your Izzet Staticaster twice in one turn? If you have a way to untap it so you can pay the cost a second time, that’s also legal!
The only exception to this is if the ability outright says it can only be used a maximum number of times in a turn, or if it’s a Loyalty ability (which have rules baggage that says they’re once-per-permanent-per-turn, but not written on the cards). For example, Beetleform Mage has a restriction on it, so it doesn’t matter how much mana you have. You’ll still only be able to pump it the one time.