Can a duration be set for an effect?

"So what in that list is supposed to be a safety net?" Stacey asks, reading the notes you've quickly scribbled down.

"I haven't added it yet, we need to do some more testing first babe. To see if it will actually work" you reply.

"OK, so whats the next test?" she asks.

Looking at her, you see she has the marker in hand, twirling it between her fingers. "Next I want to see if an effect can be made to last for a specific period of time, and if it reverts back after."

"Can I test this one on you?" she asks excitedly. "I have a great idea for testing that".

"Stacey, YOUR the guinea pig for these tests remember." you say, holding your palm out for the marker. She pouts and places the marker in your hand. "Whats your idea?" you sigh.

"FULLY ERECT FOR THREE MINUTES" she says quickly with a cheeky smile spreading across her face.

"That could work babe, but that kind of fun I was saving for a little later."

"How are you gonna test it on me then?" she asks pouting her lips at you, slouching.

"I'll show you". You grab her arm again and start writing along it. Stacey gasps as you lift the marker from her skin and your pleased to see her chest swell, her tiny top stretching and straining to contain the now F cup breasts she'll have for the next minute. You can see her hard nipples poking through the material, and with a naughty thought, reach over and gently stroke, causing her to let out a soft moan.

After roughly a minute of playing with her nipples, her breasts start to reduce in size, her now stretched shirt ill fitting on your girlfriend. Looking down at her arm you see the words are no longer there. 'Yes, we have a safety net' you gleefully think. "Well now that there is our safety net" you say, looking up at Stacey.

"How so?"

"We can.....program if you like, a termination time into changes we make to each other. So I could make you my ****, and set the time period, after which you would revert back to normal, and again the text would also erase itself." you say excitedly. "Therefore protecting us from any accidental changes lasting indefinitely".

"Unless the words are erased or altered" Stacey adds.

"Ah, yes, but that.......still needs testing" you respond flipping your pad back over to your test list, pointing to 'Can words already written be added to to alter affect?'

"OK, so whats next?"