Went through the same nonsense in Porto last year. Ended up at a little shop near the metro where the guy just asked for my passport and sold me a prepaid card, no tax ID, no address, nothing. Walked out in five minutes. The big chain stores are useless for this, they follow the rules too strict. Found out later that if you hit up the smaller kiosks or even some corner tobacco shops, they'll bypass half the paperwork. My friend got one in Faro just by showing his hotel booking, so it's a total lottery depending on who's behind the counter.

Kept mine in the back of the fridge for almost a month one time when I got busy with work and totally forgot about it... smelled like nail polish remover when I opened the jar. Fed it twice over two days and it came back stronger than before, honestly felt like it was more active than when I left it. I think the cold just slows them down so much they kind of hibernate rather than die. Now I don't stress about leaving it for a couple weeks, just make sure it's fed before I tuck it away.