Ref. No. 2845/45-4479
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
Only the money (6 lakh) you invested in the insurance plan is yours. The additional amount (5 lakh) you got is the interest amount, which is not Halal for you. The Interest amount must be given to the poor without the intention of reward.
﴿ يَآ أَيُّهَا الَّذِينَ اٰمَنُوآ اِنَّمَا الْخَمْرُ وَالْمَيْسِرُ وَالْأَنْصَابُ وَالْأَزْلَامُ رِجْسٌ مِّنْ عَمَلِ الشَّيْطَانِ فَاجْتَنِبُوهُ لَعَلَّكُمْ تُفْلِحُون﴾ [المائدة: 90]
" عَنْ عَمْرِو بْنِ يَثْرِبِيٍّ، قَالَ: خَطَبَنَا رَسُولُ اللهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: «لَا يَحِلُّ لِامْرِئٍ مِنْ مَالِ أَخِيهِ شَيْءٌ إِلَّا بِطِيبِ نَفْسٍ مِنْهُ»". (شرح معانی الآثار،(2/313 ، کتاب الکراهة، ط: حقانيه)
And Allah knows best
Darul Ifta
Darul Uloom Waqf Deoband