Giving your customers a free trial for your product can get you many sign-ups, but no revenue. This is a struggle for many start-ups, to get their customers with free accounts to upgrade to a paid plan, the best way to achieve this is to set limits for the free accounts, such as: restricting the number of monthly usages, completing one action for a specific number of times, log-in frequency, add interruptions, etc. Set a limit to the length of your free trial, so users are exposed to what your product has to offer and once their trial is finished they can receive an invitation to maintain these benefits.