Assalamu alaikum
I went to a store to buy a sim card. The sim card was sold for free but i had to make my first recharge of that sim with the seller himself.
Is this transaction valid?
I downloaded some softwares using that sim card, if the transaction is invalid do i need to remove those softwares downloaded using that sim card?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.

The basic principle in trade (buying and selling) is that it is permissible unless there is a reason which makes it prohibited.

The transaction that you mentioned can be adapted into a permissible form of compensation.

Allah knows best.