My old phone would only hold one sim so when I returned home I put my US sim back in. The phone I have now holds two sim cards and I can select which one the phone uses so I do not have to take one out and put the other in anymore.
As far as keeping it active. After we're done using the Lime sim I do nothing to keep it active. I use the online etop a few weeks before we return and we have been good to go for the past 3 years. Each top up has been just short of one year from our last use of the Lime Jamaica sim.