You can use the `strategy.opentrades.entry_bar_index` built-in variable to get the bar index of the open trade. Then compare it with the current bar index.
n = 50 open_idx = strategy.opentrades.entry_bar_index(strategy.opentrades-1) diff_idx = bar_index - open_idx if (diff_idx >= n) strategy.close("buy")

You can use the `strategy.opentrades.entry_bar_index` built-in variable to get the bar index of the entry. Then add a check based on current bar index.
entry_idx = strategy.opentrades.entry_bar_index diff = bar_index - entry_idx if (diff > 10) strategy.close("Long")