Touch Effects And Holding The Charge
Some effects, most notably spells, have a range of touch (see Range below) and require an action to activate. In most cases, if you don’t discharge a touch effect on the round you create it, you can postpone the discharge of the effect (also known as holding the charge) indefinitely. You can make touch attacks round after round until the effect is discharged. If you make any other attack, activate another ability, or cast a spell during this time, the touch effect dissipates.
Some touch spells allow you to touch multiple targets as part of the spell. You can’t hold the charge of such a spell; you must touch all targets of the spell in the same round that you finish casting the spell.
Source
Core Rulebook pg. 271