In a monetary model based on Lagos and Wright (2005) where unsecured credit and money are used as means-of-payments, we analyze how the cost and quality of the record-keeping technology affect welfare. Specifically, monitoring agents’ debt repayment is costly but is essential to the use of unsecured credit because of limited commitment. To finance this cost, fees on credit transactions are imposed, and the maximum credit limit that is incentive compatible depends on such fees and monitoring level. Alternatively, the use of money avoids such costs. A higher credit limit does not necessarily improve welfare, especially when the limit is high: the benefit from increased trade surpluses from a higher credit limit is offset by the increased cost of monitoring to achieve the improvement. Moreover, under the optimal arrangement, optimal credit limit decreases with the marginal cost of monitoring. When the cost is sufficiently low, a pure credit equilibrium is optimal. When the marginal cost is high, it is optimal to have a pure-currency economy. But when the cost is at an intermediate level, we show that credit is sustainable but not socially optimal. In this range, the implementable credit limit leads to a higher trade surplus than in a pure monetary economy, but owing to the cost of operating the record-keeping system, social welfare in credit equilibrium is lower than the welfare in a pure monetary equilibrium. In addition, we show that there can be a non-monotonic relationship between the optimal record-keeping level and the optimal credit limit.