Restriction::canUse

static function canUse($entityCode, $userId = 0, $forceUpdate = false)
{
	// you can readwrite field values, but editing scheme is not guaranteed
	if (
		static::hadUserFieldsBefore($entityCode, $forceUpdate)
		|| Bitrix24Task::checkFeatureEnabled(Bitrix24FeatureDictionary::TASKS_USER_FIELD)
	)
	{
		return true;
	}

	return !TaskLimit::isLimitExceeded((TaskLimit::isLimitExist() ? 0 : UtilRestrictionBitrix24RestrictionLimit::DEFAULT_LIMIT));
}