This is why it's not always good to have credit between friends as it may cause some conflicts or worst may end the friendship. But seriously, why should it last a year before settling it? Anyway, if my friend owes me 0.1 btc I think the decision will be based on the agreement beforehand, that is if we had one. But if none, maybe we can talk it over a coffee and come up on a win-win situation. And of course I will still consider his situation if he is capable to pay back the same btc amount or maybe I'll just ask the last year's equivalent of how much he owes me. But if a year really passed by, maybe that 0.1 was nothing to me so if there's no chance I can get it back then that's life. We will still be friends but I don't think I can be able to lend him again, haha!