We have no limits on FREE subscription plan use, i.e. you can use it as long as you want.
This plan only has a limited number of templates (no more than two), exports (4 per month), test emails (5 per day) and Timer block views (1000 per month).
All counters are reset next month, on the same day when the plan was activated. For example, you registered on 03/12/19 and spent exports limit in 2 days, therefore new exports will be available on 04/12/2019.